Blueberry Oatmeal Crumble Bars


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Blueberry Oatmeal Bars — These bars are buttery and packed with blueberry flavor! They take just 10 minutes of prep and then go straight into the oven. So easy to make, and a crowd pleaser every time!

four blueberry bars with oatmeal crumble topping on white plate

Best Ever Blueberry Crumble Bars

This blueberry crumble bars recipe is an easy, one bowl, no mixer recipe that takes just minutes to make. I adapted the recipe from my Blueberry Pie Bars by reducing some of the flour and adding oats to the crust and crumble mixture. The oats add such great texture.

The crust and oatmeal crumble topping are one and the same. Love it when that happens so there’s one less step and one less bowl to wash! 

The blueberry oatmeal bars aren’t overly sweet and the blueberry flavor shines beautifully, which is why they’re great for breakfast, brunch, snacks, or a healthy dessert. They’re soft and tender, yet slightly chewy from the oats, and I’m a sucker for anything with a crumble topping.

close up of blueberry bar with oatmeal crumble topping

Ingredients for Blueberry Oatmeal Bars

To make the oatmeal blueberry bars, you’ll need: 

  • Unsalted butter
  • All-purpose flour
  • Old-fashioned oats
  • Granulated and brown sugar
  • Salt
  • Blueberries
  • Lemon juice
  • Cornstarch 
Blueberry Oatmeal Crumble Bars - Fast, easy, no-mixer bars great for breakfast, snacks, or a healthy dessert! BIG crumbles and juicy berries are irresistible!!

How to Make Blueberry Bars with Oatmeal Topping

This blueberry crumb bars recipe has been a reader favorite for years, both because the bars are delicious and because the prep work is so simple! 

  1. Make the crust / topping mixture: Melt the butter in a large bowl before adding in some flour, oats, two types of sugar, and salt. Stir all of that together. Note that the mixture should be dry and sandy at this stage. 
  2. Set some of the mixture aside to be sprinkled on later as the oatmeal crumble topping, then transfer the rest to a greased 8×8-inch baking pan. Pack the mixture into the pan with your hands or a spatula (just make sure it’s packed down into an even layer and covers the entire pan). 
  3. Make the blueberry filling: In the same bowl you made the topping in, add some blueberries, cornstarch, lemon juice, and sugar.
  4. Toss to combine, then spread the blueberry filling over the crust. 
  5. Sprinkle the reserved crumble topping over the blueberry layer before popping the blueberry bars into the oven.
  6. Bake: The edges should be just set and the oatmeal crumble topping will be golden. 
Blueberry Oatmeal Crumble Bars - Fast, easy, no-mixer bars great for breakfast, snacks, or a healthy dessert! BIG crumbles and juicy berries are irresistible!!

Blueberry Bars FAQs

Should I Use Fresh or Frozen Blueberries? 

I used frozen blueberries for these blueberry crumble bars, but I’m sure fresh would work as well. If you’re using fresh blueberries for these bars, I recommend reducing the bake time by 10 to 15 minutes (I haven’t made this recipe with fresh berries, so I can’t say for certain). When evaluating the doneness of your bars, it’s more important to decide based on how the bars look rather than how much time has passed. 

Can I Use Instant Oats? 

Don’t use quick cook or instant oats because they’re finer than old-fashioned oats and behave like flour. Instant oats will make mixture too dry. 

Can I Use Another Type of Berry? 

Yes, of course! I’ve also made Strawberry Bars, Mango Bars, and Cranberry Bars using this same base recipe. 

Can This Recipe Be Doubled? 

Yes! I made this recipe for blueberry oat bars in a 8×8-inch pan, but you should be fine to double the recipe and bake the blueberry crumble bars in a 9×13-inch dish. 

Can Blueberry Bars Be Frozen? 

Absolutely! These bars freeze incredibly well and will last up to six months if sealed tightly in a freezer bag or freezer-safe container. So go ahead and make a pan or two of these bars when blueberries are in season and thaw them out when you have guests coming over! 

Can the Topping / Crust mixture be made with coconut, almond, or oat flour?

I haven’t ever tried any of those flour alternatives, so can’t say for sure. My hunch is no, you can’t use anything besides all-purpose flour, because the flour serves the purpose of making both the crust and crumble. I would stick with all-purpose flour OR use a gluten-free all-purpose flour baking substitute if that’s the issue for you.

Blueberry Bars with Oatmeal Crumble Topping — These bars are buttery and packed with blueberry flavor! They take just 10 minutes of prep and then go straight into the oven. So easy to make, and a crowd pleaser every time!

Tips for the Best Blueberry Bars

Cooling time: I should note that you can’t eat these bars straight out of the oven. These blueberry bars need time to cool and set (around 30 minutes or so). If you try to cut into the bars right away, they’ll fall apart in your hands and will likely scald the roof of your mouth. 

Lemon blueberry bars: To make blueberry bars with a hint of lemon flavor in the filling, add the zest of a lemon to the filling. Don’t add extra lemon juice, as that would make the filling too runny. 

Frozen berries: If using frozen berries, do not thaw them first. Add them to the filling straight from the freezer. 

Blueberry Bars with Oatmeal Crumble Topping — These bars are buttery and packed with blueberry flavor! They take just 10 minutes of prep and then go straight into the oven. So easy to make, and a crowd pleaser every time!

Recipe Video

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Yield: 8 servings

Blueberry Bars with Oatmeal Crumble Topping

Blueberry Bars with Oatmeal Crumble Topping

These Blueberry Bars with Oatmeal Crumble Topping are buttery and packed with blueberry flavor! They take just 10 minutes of prep and then go straight into the oven. So easy to make, and a crowd pleaser every time! 

Prep Time 10 minutes
Cook Time 55 minutes
Cooling Time 30 minutes
Total Time 1 hour 35 minutes


Crust and Crumble Topping

  • 1/2 cup (1 stick) unsalted butter, melted
  • 1 cup all-purpose flour
  • 3/4 cup old-fashioned whole-rolled oats (don’t use quick cook or instant, they’re finer and behave like flour and will make mixture too dry)
  • 1/2 cup granulated sugar
  • 1/4 cup light brown sugar, packed
  • pinch salt, optional and to taste

Blueberry Layer

  • 12 ounces (2 cups) blueberries (fresh or frozen; I used frozen and didn’t thaw)
  • 1/3 cup granulated sugar
  • 2 tablespoons lemon juice
  • 2 teaspoons cornstarch


  1. Preheat oven to 350F. Line an 8-inch square pan with aluminum foil and spray with cooking spray; set aside. Lining the pan helps with cleanup and is recommended.

Make the Crust and Crumble Topping

  1. In a large, microwave-safe bowl melt the butter, about 1 minute on high power.
  2. Add the flour, oats, sugars, optional salt, and stir to combine. Mixture will be dry and sandy with some larger, well-formed crumble pieces.
  3. Set 1 heaping cup mixture aside to be sprinkled on later as crumble topping.
  4. Transfer remaining mixture to prepared pan, and using a spatula or your fingers, hard-pack the mixture to create an even, smooth, flat crust; set aside.

Make the Blueberry Layer

  1. In a large mixing bowl (same one used for crust and crumble is okay), add all ingredients and toss to combine. If sugar hasn’t dissolved fully that’s okay because it liquifies while baking.
  2. Evenly distribute blueberry mixture over the crust.
  3. Evenly sprinkle with the reserved heaping 1 cup crumble topping mixture. Before sprinkling, I squeeze the mixture in my palm to encourage bigger crumble pieces to form.

Bake the Bars

  1. Bake for about 55 minutes, or until edges are set and center has just set. Crumble topping should appear set and very pale golden. I used frozen berries without thawing and the pan was very cold going into the oven. If using fresh berries, baking time will be reduced, but I’m not sure by how much, I’d guess at least 10-15 minutes, possibly less. Bars may take longer than 55 minutes if blueberries are very juicy. Watch your bars, not the clock, when evaluating doneness.
  2. Place pan on a wire rack and allow bars to cool for at least 30 minutes before slicing and serving. If you try to slice bars before they’ve cooled completely, they’ll be extremely messy and could fall apart. Bars will keep airtight at room temperature for up to 1 week, in the fridge for up to 10 days, or in the freezer for up to 6 months.


Nutrition Information:



Serving Size:


Amount Per Serving: Calories: 414Total Fat: 12gSaturated Fat: 7gTrans Fat: 0gUnsaturated Fat: 4gCholesterol: 31mgSodium: 22mgCarbohydrates: 62gFiber: 2gSugar: 33gProtein: 4g

More Desserts Using Blueberries: 


Blueberry Pie Bars — Super soft, easy bars with a creamy filling, streusel topping and abundance of juicy blueberries.

Blueberry Crisp — The sweet juicy blueberries contrasted with the crispy and crumbly oat-based topping is just perfect!

Crustless Blueberry Pie – A FAST, crustless, no-mixer dessert that’s perfect for summer entertaining, picnics, or potlucks!! Somewhere in between pie, cake, and blondies is what you get with this FABULOUS blueberry dessert recipe!

Lemon Blueberry Bundt Cake with Lemon Glaze — Almost more berries than cake in this soft, fluffy lemon blueberry bundt cake! The lemon glaze is plate-licking delish!!

Lightened Up Blueberry Lemon Pound Cake — The blueberry-lemon combo is always a win, and so is pound cake that won’t break your caloric piggybank. This Lemon Blueberry Pound Cake is a keeper!

Blueberry Muffin Cake — This fast and easy cake tastes like a big buttermilk pancake that ran into a blueberry muffin on the way to the oven.

Blueberry Zucchini Bread— This blueberry zucchini bread is a quick, no-mixer recipe that’s sweet, but not too sweet. Each bite is bursting with fresh blueberries!

Blueberry Cream Cheese Cake — A light and tender blueberry sponge cake stuffed with tangy-sweet cream cheese filling and bursting with juicy blueberries in every bite! An EASY, no-mixer cake recipe that’s sure to be a family FAVORITE!!

Cream Cheese-Filled Blueberry Cake - A light and tender blueberry sponge cake stuffed with tangy-sweet cream cheese and bursting with juicy blueberries in every bite! An EASY, no-mixer cake recipe that's sure to be a family FAVORITE!!

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Welcome to AverieCooks! Here you’ll find fast and easy recipes that taste amazing and are geared for real life. Nothing fussy or complicated, just awesome tasting dishes everyone loves!

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Please note: I have only made the recipe as written, and cannot give advice or predict what will happen if you change something. If you have a question regarding changing, altering, or making substitutions to the recipe, please check out the FAQ page for more info.

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  1. These are so yummy! I used 1/2 almond flour and 1/2 white whole wheat flour….they turned out great!

    Rating: 5
    1. I am happy to hear they are yummy and worked well for you with the flour combos and types you used!

  2. These bars are delicious but the large volume of ads in the post and recipe make it very cumbersome to use.

    Rating: 5
    1. I haven’t ever tried any of those so can’t say for sure although my hunch is no because the flour serves the purpose of making both the crust and crumble so I would stick with AP or use a GF-AF if that is the issue.

  3. I’d like to try these but can’t see any quantities for ingredients. Also, the popup ads on this site make it almost impossible to read.

  4. I made these bars last night for Sunday night dinner. They were a huge hit. As with All Recipes I use the recipe as a base and I personalize it .I doubled the recipe baked it in a 9 by 13 Pan buttered the Pan , used no foil or parchment paper. I added sliced almonds and cinnamon to the oat butter mixture.. For the blueberries I used frozen blueberries . I cooked it on a stove top , first, to activate the cornstarch lemon juice and to thicken up the juice that the blueberries will exude once they get heated up. I let cool down a little bit before I put it on the oat mixture. Baked 45 minutes and let it cool in pan for an hour before i served them. It was perfection. Thanks for the’ berry-good ‘ recipe. Risha

    Rating: 5
    1. I am glad these were a huge hit and that you were able to add almonds and cinnamon to the mixture and that frozen blueberries worked just fine for you!

    2. *Risha* thank you for your comment, I was hesitant about using my juicy frozen berries, and I followed your example of cooking them stovetop first. Produced a wonderful blueberry filling that baked perfectly with the bottom layer and topping. Thank you and thanks to Averie for this nice recipe.

  5. Hi I just made your Blueberry oatmeal crumble, and it tastes really good, the only issue is had was it sticking to the foil.
    I sprayed the foil with cooking spray like you suggested, I let it cool completely.
    I even put it in the refrigerator to chill, but it still stuck.
    So now instead of bars I have a crumble.

    What did I do wrong?


    1. Some foil is just that way. I always bake with this foil. When sprayed, it never ever sticks!

      Also the foil is optional but for me I can’t cook without it because I don’t like doing extra dishes later :)

  6. Hi there I was wondering if I can use Splenda instead of sugar for the Blueberry oatmeal crumble bars.

    If I double the recipe will it take longer to cook?


    1. I am not sure, I have never baked with Splenda so can’t answer that.

      Possibly a bit longer, but if you bake it in a 9×13 pan, not much longer, maybe 5ish minutes or so. But cooking with Splenda could also effect baking time, so keep that in mind.

  7. The blueberry crumble bars were a major hit! I did use extra-thick oats and they came out great. I really appreciate your explanations of why to use particular ingredients (like don’t use the quick-cook oats because they act like flour in this recipe). Thank you so much for this delicious recipe:)

    Rating: 5
    1. Thanks for the 5 star review and glad these were a major hit! And I am glad you appreciate my explanations and tips, that is nice for me to know they are appreciated.

  8. Just made this tonight – delicious! And a great kid-friendly recipe for when the littles want to help mix :)

    Rating: 5
  9. for some reason, I tipped it upside down and the blueberries and toppings fell out so when I put it back in the toppings were mixed in with the blueberries. It still tasted good, would recommend but don’t tip it upside down. lol :).

    Rating: 5
    1. LOL! Thanks for the 5 star review and glad that this was still good even after a little mishap!

  10. When I made these, my crust crumble mixture was like dough, not crumbly. I even added an extra 1/2 cup of flour. Still turned out tasty, though. Is there something in the recipe that is misprinted? I’m a seasoned baker, and the only way I could see this getting crumbly is by cutting in the butter. I will definitely try it again!

    Rating: 4
    1. There are so many things but I would use King Arthur flour when baking, it’s got slightly more protein (gluten) and is insurance against these types of things because if you added 1/2 cup more flour, I am guessing your flour is a very soft flour, like Gold Medal or a no name brand. Also because of summer humidity, you will likely need to use more flour regardless for things but if you’re a seasoned baker then you know that.

      Also you want to use a light hand when mixing it together, sort of spoon, fluff, turn over, mix it with a fork not a spoon so you don’t have the temptation to ‘stir’. All of these things should help the mixture be more of a crumble for next time.

  11. Made with fresh blueberries, decreased the sugar in the blueberry filling for health reasons, and baked for 45 minutes. Came out perfect! Ppl need to remember to let cool completely

    Rating: 5
    1. Thanks for the 5 star review and glad that they came out great with less sugar and fresh berries, and yes, cooling completely is the only way with these!

  12. These bars were wonderful. I had fresh blueberries so I used 2 1/2 cups, which is what I had on hand. Turned out perfect bars. Thanks for the recipe.

    Rating: 5
  13. How do you tell when it’s “set”? My over takes an extra long time to bake everything, so it’s tricky for me to tell when things are done. I let it bake an extra 10 minutes, and it looked like yours did in the video. It turned out too mushy to be eaten as a bar though. It’s still delicious, but you have to eat it with a fork.

    Rating: 5
    1. Thanks for the 5 star review! Then it wasn’t set if it was too mushy to eat as a bar OR you just had really juicy berries. Either way, you probably could’ve baked a bit longer for a firmer texture but a fork works just fine too.

  14. This is an easy, delicious recipe.I made it once before with blueberries and today I used strawberries. Yum!

    Rating: 5
    1. Thanks for the 5 star review and glad it was easy and delicious and you are mixing up the fruit options!

  15. About a month ago, I made this recipe with fresh blueberries and one small change  (Browning the butter while melting it because I don’t have a microwave and it only takes a couple minutes extra on the stove) the bars only took 45 minutes to bake and turned out absolutely delicious, and even impressed my mom who is a much better baker than I am! I’ve made the recipe again today, using blackberries that were getting a bit sad in the fridge… once again, absolutely delicious. My only complaint is that I can’t stop eating them! 

    Rating: 5
    1. Thanks for the 5 star review and glad this recipe has impressed your mom, works with sad-ish blackberries, and I am sure the accidental browned butter since you don’t have a micro is absolutely delish! I love browned butter in any baked good!

  16. Delicious recipe and very quick to put together! I used instant oats (that’s all that was in the pantry), and I had no issues with dryness. Came out perfectly!

    Rating: 5
    1. Thanks for the five star review and glad that the instant oats worked without any dryness issues!

  17. this has quickly become a staple in our home!! it’s soooo fabulous! I use coconut oil instead of butter though for a healthier version and I add lemon zest to the blueberry mixture. Sooo yummy. I have noticed too that when using fresh over frozen you want to use about 2 cups of fresh and only 1.5 cups for frozen. This is such an amazing and easy recipe. I speak for my whole family hen I say thanks for sharing this one!!

    Rating: 5
    1. Thanks for the five star review and I’m glad it’s a staple! I bet the coconut oil and lemon lest add such a great touch!

      Good to note that 2c fresh and 1.5c for frozen berries based on your experiments!

  18. I made this recipe yesterday but doubled it in a 13 by 9 pan and everyone loved it. I love that it has a bottom crust because berries always stick to any pan I use if I put them in the bottom. I loved it and will make it again!!

    Rating: 5
  19. Hi! Made these but mine came out more like a cobbler. I waited until everything was cooled but these were too wet to hold a bar shape. Do you know if I need to bake them longer?

    1. Yes bake a bit longer. Or perhaps your berries were just especially juicy at this point in the summer, I wouldn’t be surprised. Which is going to make this more cobbler like and less bar-like. You can always make more crust/topping and play around with those ratios if you want it in a true bar form. Or use less berries possibly. I am sure they tasted great despite the shape.

  20. Made this recently and it was so easy and delicious!! I’ve made so many of your recipes and they never disappoint! You’re my go to for any recipe!

    Rating: 5
    1. Thanks for the 5 star review and glad you enjoyed this and thanks for the compliments on my recipes! I really appreciate hearing that they never disappoint for you!

    2. Thanks for the 5 star review and glad I am your go to for any recipe! That is such a high compliment and praise and I appreciate your support!

  21. I love this recipe. I doubled it and baked for 55 minutes in a 9×12 pan. The only problem I ran into is the cookies sticking to the bottom although I sprayed the pan. I would spray more or use parchment paper next time.

    Rating: 5
    1. Thanks for the 5 star review and glad you love the recipe! Yes baked fruit/juices are sticky, just spray extra well next time or use nonstick foil like I suggest.

  22. I just had the first bar. I want to eat the rest of them NOW. They are even better than I thought and was hoping they were going to be. I used salted butter and eliminated the lemon juice, I didn’t make any other changes. I know I will probably be making these more often than I should. Also, they are so easy to make .

    Rating: 5
  23. I have cut out sugar. Can I make this using Swerve and or Stevia? Those are the only ones I know of not to raise blood sugar. I would attempt this using Almond Flour instead of regular flour as well which will also make it healthier and lower carb. I will play around with this and see if I can make it Whole 30 and/or keto so that I can eat it because it looks too good not to try to make it for my woe. Thanks, I do use your recipes when they fit into my eating plan and have found them wonderful as I am sure this one is, too.

    1. Yes please play around with it. That is the only way you will know for sure. I haven’t tried to modify the recipe from what is written.

  24. these are superb fruity recipes! trouble is, about 50% of adults can’t assume 62 grams of carbohydrates in one serving. please create the same wonderful recipes without high carbohydrates and you’ll have fans for life!
    best regards, Julie Stroeve, Minneapolis

  25. I have tried this one with blackberries as I had them in the fridge and I bet it came out not worse than with blueberries.

    Rating: 5
  26. Just made these this weekend. They came out great! Killer recipe. total keeper, Averie. Thanks! I made a second batch using frozen mixed berries (blueberries, cherries, raspberries, and blackberries). That also came out fantastic. With summer just around the corner I’m gonna try it with stone fruits and also a mix of berries and stone fruits. Also going to try using browned butter.

    1. I’m glad these are total keepers for you and you will be making more it sounds like!

  27. These look so good! Do you think they would work with either chopped frozen cherries or diced apples? Also, could I substitute refined coconut oil for the butter?

    1. Not sure on any of your questions since I have not experimented with them. Coconut oil instead of butter though, not really since it will just melt and not lend to making the crumbles this recipe has.

    1. Thanks for the five star review and I’m glad you make these often and with raspberries, too!

    1. I think if you double the recipe and bake it in a 9 x 13 pan you’ll be fine, although I haven’t personally tried it, but I think it will be fine.

  28. These were amazing! I made them exactly how you said except omitted lemon juice and I used a glass 9×7 baking dish. They came out great! This one is bookmarked for sure. Thank you!!

    1. These are amazing! I love the crumb topping.I made a half batch using fresh blueberries and cooked for about 40 minutes.I can’t wait to try again mixing in other berries.

      Rating: 5
      1. Thanks for the 5 star review and glad they turned out amazing! And yes a very flexible recipe so I hope you enjoying experiments with other fruits and berries!

  29. These are awesome and easy, as everyone claims, but they are basically CANDY. They don’t need to be as sweet or buttery as they are, imo. I left out a quarter of the sugar in the crumble crust, and it’s still way too sweet. Next time I’ll halve the sugar and use at least a quarter less butter. They’ll still be amazing.

    Rating: 4
    1. Everyone’s preferences for sugar, salt, etc. vary. What one person thinks is candy, another person sees as a breakfast bar that has just the right level of sweetness. To each their own. Glad you enjoyed the recipe!

  30. Do you think I could freeze this and it would thaw nicely?I’d like to have it Christmas morning.I’ve made it once before recently and it was a big hit!!

    Rating: 5
    1. We’re so close to Christmas that if you’re trying to make this for Christmas, I would just keep them covered nicely on your countertop in an airtight container. I would not bother freezing. Freezing is just going to dry things out in the end, and it’s for long-term storage. We’re talking three days here at this point, just keep it at room temperature covered well.

  31. Made this exactly like the recipe! MY HUSBAND and my MOPS group loved them. Has anyone tried them with fresh apple?

    Rating: 5
      1. Yes that is the correct. Although note that nutrition stats are provided as a courtesy and are computer generated.

  32. Just tried this recipe and we love it! So easy to make – one bowl and no mixer – and I don’t have to remember to soften butter ahead of time. I used fresh blueberries that were pretty juicy, so I added a couple of tablespoons of flour to the blueberry mixture to make sure it was thick enough. This is a keeper and will definitely make again and again. Thanks Averie.

  33. Oh Em Geeeeeee!
    Amazingly GOOD & easy!
    You had me at melting the butter instead of having to cut it in.
    Crust is do buttery & oaty & a perf CT platform for the filling.
    Chilled bars get better & better 👍
    I used fresh blueberries & plan to try sour cherries, peaches, plums. Seedless grapes?

    1. Glad these are a hit with you and I agree, melted butter is just SO much easier than trying to cut butter in!

  34. We love this recipe. It’s so easy and yummy. At least with the blueberries and oatmeal, it seem a little more healthy! Thanks,

  35. Hi Averie! I love making these bars and they’re always a hit whenever I do. Just a question though: Is there a way to make sure the filling isn’t too runny/the bars don’t fall apart? I’m never able to get the nice, solid bars you’re able to in your pictures. The only time I sort of do is when they’re in the fridge but once I take them out they start to fall apart easily. The only substitution I’ve ever made was using bottled lemon juice instead of fresh but they come out the same no matter what I do. Should I try adding more cornstarch to the blueberry layer?

    Rating: 5
    1. Thanks for the 5 star review and glad you love these bars! To make them more solid, I would increase the amount of flour by a couple tablespoons and see if that helps. Corn starch will not do the trick I don’t think. Also use King Arthur brand flour. So much better for baking than other brands and I find it really helps add structure to my baked goods.

  36. This has been a go to now for a couple years. Each time I make it i am reminded how easy as well as delicious it is! Always get compliments from guests.

    Rating: 5
  37. I love how I already had all the ingredients and so I decided to make it on a whim today. I used gluten free flour instead since my hubby can’t have gluten. He totally loved it and said it was soo good. Thanks for the easy recipe.

    Rating: 5
    1. Thanks for the 5 star rating and glad it came out great for you! Good to know GF flour was a success, too!

      1. I created a monster. He ate the whole pan in 2 days and wanted more but wanted to double it. 😳

  38. A family favorite. Made these many times with a little more healthier version by using only whole wheat flour, and only a scant 1/2 cup of coconut palm sugar ( instead of white or brown sugar) in crumble mixture as well as a heaping 1/2 tsp of cinnamon.
    I also sprinkled just a little coconut palm sugar ( no white sugar) over blueberries with the lemon juice and cornstarch.
    Used frozen Oxford wild blueberries ( these are sweet on their own) and baked for about 45 – 50 minutes. These are excellent squares. Everyone really enjoys them. Thank you so much for this recipe.

    1. Thanks for letting me know these are an absolute fave of yours and that you have even healthified them a bit!

  39. going to try this for Christmas with ice cream. Will try to switch it up a notch. Mixed berries, coconut, cinnamon ….will try it and let you know how it goes!

  40. Thanks for sharing the recipe. Just like eating a pie but portable!!! It does a bit too sweet for breakfast bar haha… but perfect for a treat or dessert, especially during my break on hiking trip. Seriously easy and fool proof, thumbs up.

  41. I love this recipe and have made it several times. I’ve served them for dessert with a little scoop of ice cream or coconut gelato or by themselves. I’ve now started cutting the white sugar to half the amount called for in both the crust and filling and they are still sweet enough for us. Thank you for posting this!

  42. I love this recipe, as does my family. Made with blueberry, raspberry, cherry & peach. All were good. I added a little chopped crystallized ginger to the peach. Fab! Also parchment paper sprayed with spray

    1. Thanks for trying the recipe and I’m glad it came out great for you! Glad you’ve experimented with other fruits, too!

  43. I made these yesterday with my typical substitutions of whole wheat pastry flour, evaporated cane juice, and sucanat, and I omitted the lemon juice (personal preference). I also lined the pan with parchment instead of foil. I was a little worried that after removing 1 cup to reserve for the topping there wasn’t enough of the crumble mixture to make a nice sturdy bottom so I reduced the topping amount a little and added it to the crust layer. I used fresh berries and baked for 45 minutes. The bars came out awesome and husband loved them! Thank you for a great recipe.

  44. I made it exactly as the recipe except I used parchment paper. It came out PERFECT!!!!! Thank you so much for the recipe. I plan to try with local strawberries next! 

    1. I wish I had tried parchment paper instead…the foil was a DISASTER! I also used fresh blueberries and cooked longer; but, what an ordeal getting them off the foil…Never again!!!

      1. I use Reynolds nonstick foil that I spray with cooking spray for nearly 100% of my recipes that I bake in a pan and I have more than 3000 recipes on my site and I’ve never had any problems with anything ever sticking to foil but I’m sorry that you did. If you filled it using parchment paper or nothing would be better in the future then go for it. Thanks for trying the recipe.

  45. I made these last week and my husband LOVED them! He took one everyday for his breakfast. I used half fresh and half frozen blueberries and it baked perfectly. The only thing I will do differently next time is not use the foil. Even though I greased it, it was coming off onto the bottom of the bars. Next time I’ll just grease the pan. I would rather have a little more cleanup than foil getting in my way. 
    Great recipe!

    1. I use Reynolds Heavy Duty *nonstick* foil, it’s a little more expensive but it never sticks. Just as an aside and a tip.

      Glad you loved the bars and they were a big hit!

  46. The blueberry crumble bars are great. I used fresh berries and baked for 40 min and doubled the streusel. I also added vanilla and almond extract to the filling.

    1. Thanks for trying the recipe and I’m glad it came out great for you! I love both almond and vanilla extracts!

  47. Hello Averie! We don’t have fresh or frozen blueberries from where I live. Is it okay to use those in can? The only blueberries we have here is canned blueberries. 

    1. I don’t have any experience working with canned blueberries so can’t say for sure. If they are already sweetened like blueberry pie filling then I would omit the sugar.

  48. I doubled the receipt using a 9 x 13 dish. 1/2 demerara brown sugar and 1/2 blue agave for the crust along with the packed brown sugar; 1/2 butter and 1/2 coconut oil. The blueberries were out of the frig, not frozen. Checked at 40 minutes and took out at 45. They set up fairly well except around the edges. May be from the agave or may have needed another 5 minutes. I used parchment paper with a little coconut oil on it. Delicious!!! Half in tupperware and half into the freezer :-)

  49. Great recipe!  And they looked just like the picture!!  Will definitely use this recipe over and over. Highly recommend. 

  50. Loved this recipe! It has become a summer staple with fresh blueberries! I have also tried your other bar recipe (“Berry Crumble Bars”), but I think the oats in this recipe give it a nice texture! I reduced the sugar in the berries to 1/4 cup, since the blueberries I had were on the sweeter side and the recipe was perfect! Thanks for sharing the recipe!

    1. Thanks for trying the recipe and I’m glad it came out great for you! I agree, the oats in this one make it especially good :)

  51. My husband RAVED about these bars for weeks, it was almost concerning. Super simple recipe that is super delicious. We inherited 14 huge blueberry bushes with our new house, so this recipe will be with us for a long time. Wouldn’t change a thing! Thank you for sharing it.

    1. Thanks for trying the recipe and I’m glad it came out great for you!

      I am super jealous of your blueberry bushes! I just moved into a new house in San Diego (where anything grows) and I was seriously considering planting blueberry bushes but was very afraid they’d just be candy for the birds and squirrels! Sounds like it’s possible to have a homegrown crop based on your story!

  52. Thank you for a great recipe!  
    I’m too lazy to wake up early in the morning – to bake something more elaborate for breakfast; and the size of the bake fit my toaster oven – no need to use the big oven – :) 
    Although your blueberry bars were easy and fast to make, they are really good.  I had to change filling – I had 1 cup of fresh blueberries only. I took 1 diced apple – so together I had 2 cups of mixed fruit/berries. I cooked this apple briefly in sugar and lemon juice – to get rid of extra moisture. After some liquid evaporated, I mixed in starch and blueberries. 
    The crust/topping were made exactly as in your recipe and it is to die for – :) Will definitely make it again, whenever I have leftover berries. 

    1. Thanks for trying the recipe and I’m glad it came out great for you! Way to improvise with the apple + blueberries!

  53. The recipe is great! I tripled it. I am pleased with the result except that the tin foil baked onto my pan! It only peels off in little shards. I’m not sure what I did wrong, but I think I would try parchment next time or else really grease the pan.

    1. Different brands of foil vary in thickness and durability. I use very heavy duty foil. I like foil in this recipe because the juice of the blueberries, with the sugar, and the metal pan…things can get really sticky/stuck and I find foil easier but do what you think will work best. Glad you loved and tripled the recipe!

  54. The step about cooking spray is no joke. Absolutely use foil and coat the sides of the lined pan like your life depends on it!

    And don’t skimp on the foil. Make sure that bad boy is COVERED. It gets hot and bubbly before it becomes a seriously sticky awesomeness. It took me no less than 20 minutes to cut and remove 4 pans of bars (9 squares each).

    Learn from my mistakes. Use lots of foil and cooking spray.

    1. There is something about fruit + sugar + heat that produces the most seriously sticky concoction, I know! Thanks for trying the recipe.

  55. Made BLUEBERRY OATMEAL CRUMBLE BARS tonight and I can tell you they won’t last long!  I’m not a fan of white flour so I did use 1/2 white and 1/2 whole wheat.  My husband loved them.  May even try a more whole wheat and less white flour the next time.  Also I used frozen blueberries.  Thank you for sharing :)

    1. Thanks for trying the recipe and I’m glad it came out great for you! Glad that you were able to get away with some w.w. flour, too!

  56. Your blueberry bar recipe is absolutely delicious, i tweaked a few ingredients and OMG it will be one that I repeat over and over.  Thanks,  I will feature it in my blog  I will give you credit for this.  Love your blog.

    1. Thanks for trying the recipe and I’m glad it came out great for you! Glad it will be on repeat!

  57. I made these using strawberries. My husband loved them, he said they were sweet. I meant to reduce the amount of sugar due to the sweetness of the strawberries, but my mother called just as I started, so I ended up just

    following the recipe.
    My husband started suggesting other fruits to use, bananas, apples, so I will have to do some experimenting. Thanks for a great recipe.

  58. This is a perfect recipe! I didn’t change any measurements and they came out perfect. I used my gluten free flour blend one for one as you would regular flour. I can’t wait to try with cherries or raspberries. Thank you for a great recipe! This will be on rotation in our house.

  59. Hi, I’m excited to try this recipe! I’m on a chia seed kick and like to try to find ways to add them to recipes to give it a healthy boost and because they have a bland flavor they shouldn’t alter the taste here. I’m still new to using chia seeds so my question is if you have experience with them, or if anyone has suggestions, which step here they should be added? Because they can become gel-like when mixed with liquid, I was thinking of adding them to the crust/crumb topping, but I didn’t know if the melted butter would doing something weird. Thoughts? Haha I know this is such an odd question, but a girl’s got to look for ways to be healthy when eating something that sounds so delectable! Thanks!

    1. This wouldn’t be a recipe I’d add chia seeds to. There are too many things that can go wrong from the crust not setting, the crumble turning gooey on account of the chia seeds, the blueberry consistency becoming off from them – I personally wouldn’t add them here.

  60. Hi there
    I only have quick oats unfortunately! Is there any way to use quick oats yet adjust the rest of the recipe to make it turn out? Less flour??

    1. Not really possible to use quick oats in order to achieve the crumbles – you’ll need to wait until you have old-fashioned whole-rolled.

  61. Oh my goodness I made these morning and ended up serving them with vanilla ice cream for dessert. So delicious! The best blueberry baked good I’ve ever made or tastes. Thanks for the recipe!

    1. Thanks for trying the recipe and I’m glad it came out great for you! And that it was the best bb baked good you’ve ever made or tried!

    1. I can’t say for sure how things will turn out since I haven’t tried but because of the crumble topping, it’s really best to use butter to achieve the crumbles.

  62. My husband and I loved these!! I want to make another batch and I was wondering if I could use disquick in place of the flour?

    1. No you can’t because it has baking powder in it and will cause the bars rise in a way you don’t want them to. Keep on using regular AP flour as written.

  63. I made these twice in two weeks.  Second batch I reduced the white sugar in the crumble by half and didn’t pack the brown sugar.  I lowered the sugar in the blueberry goo by a touch too.  Both versions were fantastic and I LOVE how easy this comes together, no leavening ingredients, just easy peasy and only ONE FREAKING BOWL to wash.  You’re a woman after my own heart.  I brought this to a potluck and sadly I only had a postage stamp sized piece before this was gone. Loved by all. Thank you.

    1. Thanks for trying the recipe and I’m glad it came out great for you and that you were able to reduce the sugar a little, too! I love ONE BOWL recipes, too! That is so me, all the way, don’t dirty more than one bowl or break out the mixer unless it’s absolutely warranted :) Glad they were a big hit at the potluck, too!

  64. i made these a few months back and they were great!  So now I have a cup of blueberries in the freezer and some raspberries I need to use…. Living dangerously (haha) I think I’ll combine them.  Wish me luck! 

      1. I went all raspberry!  The only thing I would do different (other than skip the tin foil) is to break up the berries and paper towel blot out some of the moisture as they are more mores than a blueberry.  Nice tart flavor!

  65. I just made these. Oh. My. Gosh. These are delicious!!! I was feeling something a little bit sweeter so I mixed up some icing with confectioners sugar and it was the perfect addition!

  66. I LOVED these! This recipe is definitely going into my “Favorite Recipes” binder! Thanks for sharing!

    The only change I made was in regards to the lemon juice, I didn’t have any. So I used just a couple drops of water instead and they still turned out great! 

    1. Thanks for trying the recipe and I’m glad it came out great for you! Glad that water did the trick :)

  67. Hi Averie ~ Thank you so much for putting such Goodness out there!  I totally think your Blueberry Oatmeal Crumble Bars rock! I actually became incredibly inspired by them and created a lemony treat with your recipe as a base. I sent a shout out to you on my blog and I hope it gets you many returns!   I am kinda new at all of this so I hope I’m doing this right… 
    Here is the page:

  68. I have been staring at this recipe and the blueberry pie bar recipe for two days now.  I want to combine them because I want to do the crumble but I want the creamy yogurt with my blueberries.  My kiddos are wretched about eating fruit so I need to soften it a bit.  Will it work?  Any suggestions?

    1. Honestly, you can’t go wrong with either dessert…make them both :) They freeze fine if you don’t devour it all within a day or two anyway!

  69. This was a nice recipe, but it was wayyy too sweet.  It seemed like I was eating just sugar.  I even halved the sugar recipe, but it was still too sweet.  I think for next time, I’ll use even less sugar and more flour and oats so it’ll be a healthier treat.

    1. Everyone has different sensitivities toward sugar and perhaps your blueberries were just extra sweet to begin with and it sounds like you’re VERY sugar-sensitive if you halved it and even that seemed too much. (That’s only about 1/2 cup total in an entire dessert, including crust and topping, which is pretty minimal!). Thanks for trying the recipe.

  70. Any suggestions for what to use in place of sugar? Would honey work for the topping? I made these this morning and absolutely LOVED them just looking for a bit of a healthier version. 

    1. Just as an fyi, sugar has 16 cals per tsp and honey has 22 cals per tsp. So….I wouldn’t necessarily say honey is any better than sugar but that’s a whole other topic; they’re both still forms of sugar. But I digress :)

      Thanks for trying the recipe and I’m glad it came out great for you as written and honestly no, honey as a topping wouldn’t work b/c it would just make everything all mushy, gummy, gooey, and won’t set up. I would say if you’re really concerned, maybe just cut the pieces a little smaller :)

  71. I’ve been waiting to try this recipe for a while now. Finally did it and they turned out to be delicious! They were a little difficult to get out of the pan and could use lees sugar but were very simple and easy. Turned out fabulously the first try which is always nice.

  72. I was super excited to try these delicious looking and easy recipe, however mine never set up. And I followed the recipe EXACTLY as written. It required a good hour in the fridge just to get it cut into somewhat pieces. Tasted absolutely DELICIOUS, just not very pretty, like at all. :-/

    1. The think about berries and fruits, i.e. Mother Nature, is that no two are alike and some are just very juicy and it sounds like yours were very juicy, hence the setting up issues. I’m glad it tasted absolutely delicious despite not being as set as mine but I personally adore super juicy blueberry desserts and would have loved yours I bet too!

  73. I just made these as a Father’s Day gift for my blueberry-loving-dad and they turned out well! I had rather large, fresh berries, so I would do the same as others have mentioned and possibly double the crust portion next time for a better crust to fruit ratio (personal preference). I added cinnamon to the crust and would definitely recommend the addition of salt to the crumble/crust as well to round out the flavor. I also added some vanilla to the blueberry mixture, and next time will increase the vanilla and decrease the lemon juice as my berries were on the tart side and the finished product came out with a little bit of a pucker! With the fresh berries, my bars were bubbling and golden at 40 mins in the oven. I’m thinking a layer of cream cheese, vanilla, and sugar would go splendidly in this recipe, as well (similar to your Greek yogurt addition in your other recipe)! For those who ended up with a chewy crust, mine crisped up when I put the bars in the fridge for an hour; they were great cold.  Thanks! 

  74. I was a little unsure of what you mean by “set up” I felt like I had some pretty large blueberries so I am keeping it in the oven a bit longer. I don’t want it falling apart, but then again I also don’t want to burn it. They smell awesome can’t wait for them to get out of the oven and cooled so I can try one!

    1. Set up – not jiggly, runny, overly loose. Not sure what more I can say :)

      Use your best judgment and baking time will vary based on the berries. You never know how juicy, big/small, etc. blueberries will be. Enjoy!!

  75. These were delicious!!!! So yummy AND easy!! I found that they were a little gooey and hard to handle (not that that’s important compared to the taste ;) ) so I might make more of the crumble next time… and there WILL be a next time!

    1. Thanks for trying the recipe and if you think a little more crumble would do the trick, go for it. And/or use slightly less fruit and they’ll firm up!

  76. Love this easy and delicious recipe.  My boyfriend east blueberries every morning in his cereal.  Great change of pace.. Tks much.

  77. I put all the ingredients in a calorie calculator and it looks like a serving is around 310 case anyone else was wondering

  78. Susan V – mine stuck on the foil as well – forgot about that part! So I just sprayed glass dish and after they cooled I put them in the refrigerator and they cut easily and were perfect!

  79. These are delicious – and easy!! My only comment is that I seemed to have too much filling – so I made them again and did the crust 1 1/2 times so the crust was a little thicker and the top covered the blueberries just a little more, easier to pick up and eat! I see myself making these a LOT!!!!!!

    1. Thanks for trying the recipe and I’m glad you enjoyed them. I think filling amounts/yields can vary because of the blueberries; fresh, frozen, tiny berries, bigger ones, etc. Glad you found something that worked for you and made them easier to carry.

  80. A friend served these and they were delish.  I begged her for the recipe, followed it exactly and failed.  I foiled and greased the pan, they stuck.  My crust was chewy, I don’t think hers was. We ate them but I want a do over.  Do you have any idea what I did wrong?

    1. It’s really hard to say what you did and where you went wrong. Maybe since your friend made them and they were great, watch how she made them and see if that’s what you did. I use heavy-duty non-stick Reynold’s foil and PAM cooking spray and I really spray the foil well and never ever have issues. That will take care of that part at least. It’s just so hard to troubleshoot from afar. Thanks for trying the recipe.

  81. what do you think about leaving the lemon juice out? My son loves blueberries but he is sensitive to citrus.

    1. In your situation, I think you have to leave it out! And that things will probably be okay. The lemon juice helps the filling set up a bit but it isn’t a pie and hopefully a forgiving recipe; although I haven’t tried leaving it out. LMK if you do!

  82. Averie, these look wonderful! I love blueberries and oatmeal and crumb topping is the best! Pinning and putting on the list to try!

    1. Thanks for trying the recipe and I’m glad it came out perfectly for you as well as my other recipes you’ve made! Thanks!

  83. Great recipe…I have been thinking about making something like this! I have fresh home made blackberry jam, do you think that would be fine to substitute the blueberry sauce with the blackberry jam? I don’t want to waste it and I think this could be the perfect recipe for this?

    1. It’s not blueberry sauce I used, it’s frozen blueberries. I think jam could be a bit too runny. I mean, it may work, it may not – your call if you want to gamble with it!

  84. Just made these last night to bring to a breakfast potluck this morning, and they turned out fantastic! – Just as you pictured them. I have Celiac, so I made them gluten-free by using Trader Joe’s gluten-free oats and Cup4Cup flour. No one was the wiser. ;) I can’t wait to try them with raspberry or cherry in the filling next! Such a great grab and go breakfast! And it’s awesome that it uses staples, so I foresee this having a regular spot in my breakfast rotation.

    1. Thanks for trying the recipe and I’m glad it came out great for you AND that you were able to keep them GF with TJs GF oats and Cup4Cup. That’s great to hear! And I bet raspberry or cherry filling would be super good! (or peaches/nectarines in the summer!) If you try other variations/fruits, LMK what you do and try!

  85. One of the best desserts? That’s high praise coming from your daughter! I can totally see why too. I’d claim every single bit of crumble for myself… Sorry everyone else, you get naked blueberry bars! :)

  86. Oooh you’re getting me all excited about the prospect of summer and blueberries and fresh fruit….which is a LONG way off for us in Canada :( I’ll have to settle for these delicious looking bars. Love that crumble topping, these look just perfect!

  87. Beautiful photographs as usual! I love blueberries. Last summer, I went to the orchard alone and picked blueberries for at least an hour. It’s such a relaxing (and delicious) time.

  88. Everything looks delicious! But blueberry Pie Bars are my favourite! Can’t wait to try this recipe! Thanks for sharing <3

  89. OMG! Do you know I actually thought about writing you to ask if you had a recipe for some blueberry oat bars?! I used to get something similar from Peet’s but they were blueberry-peach and they were SO good! I so look forward to trying these! Thank you!

    1. Funny that Peet’s sold something like this…I never knew that and I don’t live far at all from a Peet’s but I admit, I don’t go in there very often at all!

  90. We always have frozen blueberries in our freeze for morning smoothies and oatmeal. I need to give these a try! Jorge loves fruit bars.

  91. OMGOODNESS that looks beautifully delicious! I am so making this once I get some blueberries. My favorite part next to blueberries are crumb toppings! :) Thanks for sharing!

  92. When I saw this this morning it was fate! I had been complaining that I had half a tub of fresh blueberries that needed to be used up, and now I have this merrily baking away, and it smells awesome!

  93. These look great! I, too, am a sucker for a good crumble. And I love how the filling is simply all fruit (and a little sugar!) Love it!

  94. It’s definitely the time of year to start working through our freezer produce. We have lots of frozen blueberries (cherries, too) and this sounds like a perfect use of them. From the other comments, I see I’m not the only one who notices the potential for using other fruits with this recipe. :)

    1. Totally could use all kinds of fruit in this recipe and yes to working through the freezer stash this time of year!

  95. I just made the Raspberry Chia Oat Bars from Oh She Glows, and those were pretty tasty, but I’m definitely making these for my next batch of oat bars- those blueberries just look too yummy!

  96. I absolutely love this! Blueberries and oatmeal go so well together and with a crumble layer on top it must be delicious. I am going to try these for sure!

  97. An oatmeal crust and crumble– better than pie and cobbler! This looks yummy and could work so well with different fruits and berries.

  98. Just stunning! Blueberry anything is a win in my book. And all that gorgeous crumble on top is making my mouth water!

  99. Crumble bars are the best. I can imagine how juicy the blueberry filling is, and I would definitely like to eat this for breakfast!

  100. I have some frozen pie cherries that have needed a home. I think they are going to be very happy they have found their recipe. Thanks.

  101. One bowl bars are definitely a winner in my book! I love that you cut these into slices, Averie! Looks perfect! Pinned!

  102. Ship me a batch of these babies and no one gets hurt.
    Seriously though, blueberries and crumbly topping in one bowl?! ALL OVER THAT. Pinning!

  103. I just bought a bag of frozen blueberries and now I know exactly what to do with them. I love crumble toppings both sweet and savory.

    1. Well isn’t that fortuitous and perfect serendipity! If you use up your berries with this recipe, LMK how it goes!

  104. LOVE it when crust and crumble are one and the same. It’s pretty much the best deal ever.
    I love your blueberry version. And it’s so versatile, too! You can try it with raspberry (ooh, and chocolate chunks) or strawberry when July rolls around. Such a great snack!

    1. pretty much the best deal ever <--- Amen to one bowl and one-mixture recipes! Such a timesaver! And totally versatile with other berries/fruit! I wish it was summer produce season right now and I'd have a field day!


    These bars, OMG. Crust, blueberries, CRUMBLE. The best things ever!

    1. You know it. Crumble to the rescue :) And I remember reading this comment last night as I was walking out the door and just now am getting around to replying. What a busy 24 hours I’ve had :)