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!
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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.
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
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!
- 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.
- 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).
- Make 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 edges should be just set and the oatmeal crumble topping will be golden.
Blueberry Bars FAQs
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.
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.
Yes, of course! I’ve also made Strawberry Bars, Mango Bars, and Cranberry Bars using this same base recipe.
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.
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!
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.
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.
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Blueberry Bars with Oatmeal Crumble Topping
Ingredients
Crust and Crumble Topping
- ½ cup unsalted butter, melted
- 1 cup all-purpose flour
- ¾ 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
- ½ cup granulated sugar
- ¼ 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)
- ⅓ cup granulated sugar
- 2 tablespoons lemon juice
- 2 teaspoons cornstarch
Instructions
- 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
- In a large, microwave-safe bowl melt the butter, about 1 minute on high power.
- Add the flour, oats, sugars, optional salt, and stir to combine. Mixture will be dry and sandy with some larger, well-formed crumble pieces.
- Set 1 heaping cup mixture aside to be sprinkled on later as crumble topping.
- 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
- 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.
- Evenly distribute blueberry mixture over the crust.
- 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
- 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.
- 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
- Recipe adapted from my Blueberry Pie Bars
Nutrition
Nutrition information is automatically calculated, so should only be used as an approximation.
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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!!
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??
Thx!
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.
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!
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!
This look so delicious! I will for sure make it tonight for Oscars! Thanks for sharing!
Can I use coconut oil instead of butter?
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.
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?
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.
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.
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!
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!
I think the combo of blueberries/raspberries would be stellar in this! Hope it turned out great!
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!
Glad you enjoyed it with the raspberries!
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!
Thanks for trying the recipe and I’m glad it came out great for you! Love your icing idea :)
These were so great, a big hit! I made the night before to let them set up, which was good.
Thanks for trying the recipe and I’m glad it came out great for you!
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!
Thanks for trying the recipe and I’m glad it came out great for you! Glad that water did the trick :)
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: https://www.prettysexyweightloss.com/Lemony-Blueberry-Oatmeal-Bars.html
Glad you’re enjoying the recipe!
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?
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!
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.
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.
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.
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 :)
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.
Thanks for trying the recipe and I’m glad it came out great for you!
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. :-/
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!