Blueberry oatmeal bars combine tender crust, jammy filling, and golden crumb topping in every delicious bite! These take just 10 minutes to throw together, have amazing flavor, and make a great breakfast, snack, or dessert.

Squares of blueberry oatmeal bars arranged on parchment paper.

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If you love berries, as we do, sometimes it’s hard to imagine having enough extra to bake with, because the berries disappear so quickly just as they are. But if you can squirrel away an extra few cups of blueberries, these oatmeal crumb bars are well worth the trouble.

You’ll love these because they’re very easy to make — the bottom and top layers are one and the same — and addictively delicious. They’re also just healthy enough to justify for breakfast, thanks to a few simple swaps.

This recipe is adapted from a similar blueberry oat bar found on Delightfully E Made, which a sweet Instagram follower recommended to me when I posted about the huge tranche of blueberries I picked with my son. We really enjoyed the original recipe, though of course that didn’t stop me from tinkering a bit!

Reducing the sugar, swapping coconut oil in for butter, and adding a smidge of lemon and cinnamon for extra flavor makes these blueberry bars a bit healthier and at least as delicious. 🙂 I also experimented with using white whole wheat flour, another modestly healthier swap which worked out beautifully. It’s safe to say you can use either that or all-purpose and get great results.

How to make them

First, melt your coconut oil (or butter) in a medium prep bowl, add dry ingredients, and stir well. You’ll then take a generous half of that mixture and press it firmly and evenly across the bottom of a 9×9-inch baking pan.

Grab a second bowl, and give the blueberries a quick stir along with some lemon juice, a pinch of granulated sugar, and cornstarch.

Why cornstarch and lemon juice?

Cornstarch ensures that the berries thicken into a jammy, not-too-runny layer after releasing their juices. Lemon juice adds zing and allows the cornstarch to stick evenly to the berries, ensuring even distribution throughout the bars.

Top the berries with the remaining crumb toppings — gaps are OK — and these bad boys are ready for the oven!

Helpful tips and tricks

  • Line Pan with Parchment. I highly recommend lining the baking pan with parchment paper, if you have it, to make it easy to remove the bars to a cutting board for clean cuts. Foil works, as well.
  • Know When They’re Done. These bars typically bake in 20-25 minutes in a 350 degree oven, but more important than the exact time are the following clues: the crumble topping should be slightly golden brown, and the fruit, where visible, should be bubbling slightly. When those two things are true, the bars are baked!
  • Let Them Cool Fully. It’s important to give these bars ample time to cool. If you try to to cut squares immediately after removing them from the oven, they will fall apart. Give them at least 30 minutes to set, preferably 1-2 hours. You can speed up the process by placing the pan in the fridge.

How to store blueberry bars

Once cut, blueberry crumb bars keep well at room temperature or in the fridge, depending on personal preference. Keeping them in the fridge will keep the texture more firm, especially if it’s very warm when you make these. We enjoy the taste either way!

View of blueberry oat crumb bars from the side, highlighting the jammy middle layer.

Adaptations and variations

  • Use Frozen Blueberries. To use frozen blueberries in this recipe, thaw them, drain well to remove excess liquid, and proceed as directed.
  • Use Other Berries. Blackberries or raspberries would be excellent in place of blueberries here. I have not tested the recipe with strawberries, but suspect they would not work as well due to strawberries’ higher water content.
  • Make a Double Batch. These can easily be doubled and baked in a 9×13” pan, with no other changes to the baking time or temperature. The bars will be a bit thicker. If doubling the recipe, you can use anywhere between 3 and 4 cups of berries.
  • Make them Gluten Free. Swap the white whole wheat or all-purpose flour for your favorite 1:1 baking blend, and use certified gluten-free oats.
Squares of blueberry oatmeal bars arranged on parchment paper.

More blueberry recipes

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Squares of blueberry oatmeal bars arranged on parchment paper.
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Blueberry Oatmeal Crumb Bars

Tender crust, juicy filling, and golden crumb topping in every delicious bite! These take just 10 minutes to throw together, have amazing flavor, and make a great breakfast, snack, or dessert.

Ingredients

  • 1/2 cup coconut oil
  • 1 and 1/4 cups old-fashioned rolled oats
  • 1 and 1/4 cups all-purpose or white whole wheat flour
  • 1/2 cup brown sugar
  • 3/4 teaspoon baking soda
  • 1/2 teaspoon ground cinnamon
  • 1/4 teaspoon salt
  • 2 cups blueberries
  • 2 tablespoons granulated sugar
  • 1 tablespoon cornstarch
  • 2 teaspoons lemon juice

Instructions

  • Preheat oven to 350 degrees F. Line a 9×9” pan with parchment, if desired, for easy removal. Set aside.
  • Melt coconut oil in a medium bowl, then stir in the oats, flour, brown sugar, baking soda, cinnamon, and salt. Mix until the dry ingredients are evenly moistened. Transfer just over half of the mixture into the baking pan, and press into an even, tightly-packed layer across the bottom.
  • In a separate bowl, combine blueberries, granulated sugar, cornstarch, and lemon juice. Toss to combine, then spread out over the bottom crust. Sprinkle the remaining oatmeal mixture evenly on top of the berries.
  • Bake for 20-25 minutes, until the berries are bubbling and the top is golden brown. Remove from the oven, let cool completely, and cut into squares.

Notes

  • Substitutions: You can easily use butter in place of the coconut oil — the two are interchangeable at a 1:1 ratio, so use 1/2 cup, or 1 stick, of butter.
  • Yield: These can easily be doubled and baked in a 9×13” pan, with no other changes to the baking time or temperature. The bars will be very slightly thicker. If doubling the recipe, you don’t necessarily need a full 4 cups of berries — anywhere between 3 and 4 cups will work well.
  • Storage: These keep well at room temperature or in the fridge, depending on personal preference. Keeping them in the fridge will keep the texture more firm, especially if it’s very warm when you make these. We enjoy the taste either way!
  • Freezing: These can be frozen, but the texture of the oat mixture on top will not be quite the same. I recommend simply making a small pan and/or sharing what you can’t use with the neighbors!

Nutrition Estimate

Calories: 159kcal, Carbohydrates: 22g, Protein: 2g, Fat: 7g, Saturated Fat: 6g, Sodium: 90mg, Potassium: 57mg, Fiber: 2g, Sugar: 10g, Vitamin A: 10IU, Vitamin C: 2mg, Calcium: 16mg, Iron: 1mg
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