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Baked banana blueberry oat bars cut into squares on a cooling rack.

Baked Banana Blueberry Oat Bars

  • Author: Steph Guinnane
  • Total Time: 1 hour 50 minutes
  • Yield: 8 x 8 Square pan 1x


Need an excuse to use up those sad ripe bananas on your counter? Look no further than these Baked Banana Blueberry Oat Bars. They are easy to assemble, use up 3 bananas, and are packed with bananas, blueberries, and brown sugary oats in each bite.



Cookie Base

  • 1 1/3 (177g) Cup All-purpose Flour
  • 2/3 Cup (74g) Rolled Oats
  • 1/2 Teaspoon Cinnamon
  • 1/4 Teaspoon Baking Soda
  • 1/4 Teaspoon Salt
  • 1/3 Cup (78g) Unsalted Butter, Softened
  • 1/3 Cup (60g) Granulated Sugar
  • 1/4 Cup (45g) Light Brown Sugar, lightly packed
  • 1 Egg (56g), Large
  • 1/2 Teaspoon Vanilla

Banana Blueberry Filling: 

  • 3 Bananas (~340g), ripened
  • 3 Tablespoons (35g) Light Brown Sugar
  • 1/4 Teaspoon Cinnamon
  • 1/4 Teaspoon Vanilla
  • 3/4 Cup (113g) Blueberries

Oat Crumble: 

  • 2/3 Cup (88g) All-Purpose Flour
  • 2/3 Cup (74g) Rolled Oats
  • 1/3 Cup (57g) Light Brown Sugar, lightly packed
  • 1/4 Teaspoon Cinnamon
  • 5 Tablespoons (71g) Butter, Cold & Cubbed


Cookie Base: 

  • Preheat oven to 350° and spray 8x8 inch pan with non-stick spray, and line with parchment paper. 
  • In a medium bowl, whisk together dry ingredients; flour, rolled oats, baking soda, cinnamon, and salt. 
  • In a large bowl or bowl of a stand mixer, cream together butter and sugars on medium speed for 2-3 minutes or until the mixture looks light, fluffy, and pale in color. Add the egg and vanilla extract and continue to mix on medium speed for another 1-2 minutes until the mixture is well combined and fluffy. 
  • Add in the flour mixture, mixing on low until combined. Scrape down the sides of the bowl to ensure all the flour is incorporated. 
  • Press dough evenly into the bottom of the prepared 8x8-inch pan. Bake for 15 minutes or until the edges of the dough turn lightly golden brown. 

Banana Blueberry Filling 

  • In a medium bowl, mash the bananas 
  • Stir in brown sugar, cinnamon, and vanilla
  • Fold in blueberries 

Oat Crumble: 

  • In another bowl, combine flour, oats, brown sugar, and cinnamon. 
  • Add cold cubed butter (~1 in./2.5cm) into dry ingredients. Using your fingers or pastry cutter, combine the butter with the flour mixture until the mixture resembles a coarse crumb. Set aside.


  • Once the cookie base is done, spread the banana blueberry filling evenly. Then add the crumble over the top.
  • Bake at 350° for 20 minutes; the top is lightly golden brown. Allow bars to cool completely at room temperature.


  • You can use either fresh or frozen blueberries for this recipe. If using frozen, do NOT defrost them before using them. 
  • If your bananas are not ripe, you can bake them at 425° for 15 minutes or until completely brown
  • Prep Time: 15 minutes
  • Chilling time: 1 hour
  • Cook Time: 35 minutes
  • Category: Bars
  • Method: Baking
  • Cuisine: Cookie Bar

Keywords: Banana, blueberries, cookie bar, oat bar