Blueberry Oatmeal Crumble Bars

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!

four blueberry bars with oatmeal crumble topping on white plate

Easy Blueberry Bars Recipe

I was going to call these blueberry breakfast bars. Or blueberry snack bars. But anytime you feel like eating juicy blueberries with buttery oat crumbles is the kind of bar they are.

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! I also eliminated the Greek yogurt, sugar, and egg from the filling and kept the focus on the blueberries.

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.

My daughter said they’re one of the best ‘desserts’ I’ve made in a long time. I made these blueberry bars on a Sunday and had breakfast ready to grab-and-go for her for the week. One less thing to worry about on busy weekday mornings! Loved that.

close up of blueberry bar with oatmeal crumble topping

How to Make Blueberry Bars

You’ll first need to make the buttery oatmeal crumble topping. To do so, 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. 

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). 

Once the crumble topping and crust have been made, move on to the blueberry filling. In the same bowl you made the topping in, add some blueberries, cornstarch, lemon juice, and sugar. Toss to combine, then spread the blueberry filling over the crust. 

Sprinkle the reserved crumble topping over the blueberry layer before popping the blueberry bars into the oven. Bake the bars until the edges are set and the oatmeal crumble topping is just turning 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!!

Tips for the Best Blueberry Bars

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. 

I should also 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. 

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! 

Blueberry Oatmeal Crumble Bars - Fast, easy, no-mixer bars great for breakfast, snacks, or a healthy dessert! BIG crumbles and juicy berries are irresistible!!

More Blueberry Recipes: 

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! 

Yield: 8 servings
Prep Time 10 minutes
Cook Time 55 minutes
Cooling Time 30 minutes
Total Time 1 hour 35 minutes

Ingredients

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

Instructions

  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.

Notes

Nutrition Information:

Yield:

8

Serving Size:

1

Amount Per Serving: Calories: 414 Total Fat: 12g Saturated Fat: 7g Trans Fat: 0g Unsaturated Fat: 4g Cholesterol: 31mg Sodium: 22mg Carbohydrates: 62g Fiber: 2g Sugar: 33g Protein: 4g

Even More Easy Dessert Recipes: 

Strawberry Lemonade Bars – Imagine crossing lemon bars with a strawberry pie. These easy bars taste like strawberry lemonade!

Strawberry Lemonade Bars - Imagine crossing lemon bars with a strawberry pie. These easy bars taste like strawberry lemonade! Sooo good!

Blueberry Muffin and Buttermilk Pancakes Cake – One of the best coffee cakes and uses a tried-and-true cake base I adore!

Blueberry and Cream Cheese Muffin Top Bread – Tastes like one big muffin top. Ridiculously soft and moist!

Lemon Coconut White Chocolate Gooey Bars — An easy, 6-ingredient recipe that will be a hit with lemon and coconut lovers.

206 comments on “Blueberry Oatmeal Crumble Bars”

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

  2. 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 :-)

  3. 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. 

  4. I cut the sugar by 2 and put more of flour. It’s very good and perfect! ;-)

  5. 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.

  6. 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!

  7. 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! 

  8. 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.

  9. 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

  10. 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!

  11. 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.

  12. Will this work with oil instead of butter?

  13. 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!

  14. 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.

  15. 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
  16. 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
  17. 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
    • 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.

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

  19. 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?

  20. I think that it will taste deliciouse

  21. 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.

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

    Rating: 5
  23. 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
    • 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.

  24. 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
    • 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!

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