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 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!
Thanks for trying the recipe and I’m glad you’re pleased and your dad is a lucky guy :)
https://www.averiecooks.com/2014/06/blueberry-pie-bars.html Exactly what you’re describing with the cream cheesey type flavor, etc. Much more ‘decadent’ than these bars which are cleaner and healthier. Try those next if you want something with even more…oomph!
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!
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!!
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!
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!
Yum! These look delicious! Going on my grocery list right now :)
Love this easy and delicious recipe. My boyfriend east blueberries every morning in his cereal. Great change of pace.. Tks much.
Thanks for trying the recipe and I’m glad it came out great for you!
I put all the ingredients in a calorie calculator and it looks like a serving is around 310 calories.in case anyone else was wondering
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!
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!!!!!!
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.
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?
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.
Do you know how many calories are in each square? Looks amazing btw. Hope to make these soon.
Not sure.
what do you think about leaving the lemon juice out? My son loves blueberries but he is sensitive to citrus.
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!
Averie, these look wonderful! I love blueberries and oatmeal and crumb topping is the best! Pinning and putting on the list to try!
Thanks for pinning!
I made these the other and as in all your other recipes I have tried, these came out perfect!
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!
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?
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!
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.
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!
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! :)
I can relate to crumble stealing :)