Blueberry Oatmeal Bars — 🫐💙 These EASY blueberry bars are buttery and packed with blueberry flavor! They have a perfect chewy meets crispy texture from the oatmeal crust and crumble topping with soft berry filling in the middle! They take just 10 minutes of prep and then go straight into the oven. So quick to make and a crowd pleaser every time! Either fresh or frozen berries are fine.
Table of Contents
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
Note: Scroll down to the recipe card section of the post for the ingredients with amounts included and for more complete directions.
How to Make Blueberry Oatmeal Bars
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.
- 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.
- Make the blueberry filling: In the same bowl you made the topping in, add some blueberries, cornstarch, lemon juice, and sugar. 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.
Want to Make Lemon Blueberry Crumble 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.
Baking 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.
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.
Absolutely! In fact, they pretty much have to be made in advance because you can’t eat these bars straight out of the oven. They 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.
However, they keep up to 1 week at room temperature and up to 10 days in the fridge. So yes, make them well in advance if you need to!
Storage and Freezing Instructions
At room temperature: Cover tightly with plastic wrap. Bars will last up to 1 week.
In the fridge: Cover tightly and refrigerate up to 10 days.
In the freezer: These bars freeze incredibly well and will last up to six months if sealed tightly in a freezer bag or freezer-safe container.
Recipe Video Tutorial
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 :)
Cheri
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Blueberry Oatmeal Bars
Ingredients
Crust and Crumble Topping
- ½ cup unsalted butter, melted
- 1 cup all-purpose flour
- ¾ cup old-fashioned 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.
Video
Notes
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!!
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!!
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
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
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
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!
*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.
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?
Thanks
Some foil is just that way. I always bake with this foil. When sprayed, it never ever sticks! https://amzn.to/3MvKZBj
Also the foil is optional but for me I can’t cook without it because I don’t like doing extra dishes later :)
Julie R.–try using parchment paper, and butter it before adding ingredients.
I’m going to give that a try right now.
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?
Thanks
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.
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:)
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:)
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.
I made several for the children at school with extra frozen blueberries . They loved them.
I made several for the children at school with extra frozen blueberries . They loved them.
Thanks for the 5 star review and glad they loved them!
Just made this tonight – delicious! And a great kid-friendly recipe for when the littles want to help mix :)
Just made this tonight – delicious! And a great kid-friendly recipe for when the littles want to help mix :)
Thanks for the 5 star review and glad it was great and the kids could help out!
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 :).
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 :).
LOL! Thanks for the 5 star review and glad that this was still good even after a little mishap!
Super easy to make and turned out delicious. Will definitely make again.
Super easy to make and turned out delicious. Will definitely make again.
Thanks for the 5 star review and glad they were delicious and that you’ll make again!
I substituted the granulated sugar with an equal amount of Lakanto Classic in both the crumble and the filling. I did not substitute the brown sugar but you could. I didn’t have lemon juice. I added a tiny bit of cinnamon to the base/crumble and a tiny bit of vanilla to the berries. These are absolutely delicious bars and I will make them again!