Blueberry Oatmeal Crumble Bars

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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.

four blueberry bars with oatmeal crumble topping on white plate

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 

Note: Scroll down to the recipe card section of the post for the ingredients with amounts included and for more complete directions.

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 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! 

  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.
  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.
  3. 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. 
  4. Sprinkle the reserved crumble topping over the blueberry layer before popping the blueberry bars into the oven.
  5. 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. 

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

Baking 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 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.

Can the bars be prepared in advance?

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

By Averie Sunshine
🫐💙 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.
Prep Time: 10 minutes
Cook Time: 55 minutes
Cooling Time: 30 minutes
Total Time: 1 hour 35 minutes
Servings: 8 servings
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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)
  • 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

Storage: 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.
Recipe adapted from my Blueberry Pie Bars

Nutrition

Serving: 1, Calories: 414kcal, Carbohydrates: 62g, Protein: 4g, Fat: 12g, Saturated Fat: 7g, Polyunsaturated Fat: 4g, Cholesterol: 31mg, Sodium: 22mg, Fiber: 2g, Sugar: 33g

Nutrition information is automatically calculated, so should only be used as an approximation.

More Desserts Using Blueberries: 

ALL OF MY BLUEBERRY RECIPES!

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!!

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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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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Comments

  1. 5 stars
    These are so yummy! I used 1/2 almond flour and 1/2 white whole wheat flour….they turned out great!