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Banana Bread Brownies

These banana bread brownies with brown butter frosting are a great way to use up ripe bananas and they stay fluffy and moist from the addition of sour cream. The rich frosting makes them dream-worthy!

Other go-to recipes with bananas to try include banana bread with cake mix, banana nut bread and mini banana muffins.

banana bread brownies on plate with fork
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Banana Bread Brownies Recipe

While I absolutely love my easy banana cream pie, these banana oatmeal chocolate chip cookies and my double chocolate banana bread, these banana bread brownies are my new recent go-to dessert!

By creating a batter that is more brownie than easy banana bread, this recipe will stun your taste buds. Moist and flavorful, the brownie is a treat in itself. But then there’s the brown butter frosting that knocks this dessert out of the park.

Recipe Ingredients

This banana brownie recipe is not only a great way to use ripe bananas but it also uses simple ingredients so you can make this easy treat anytime!

banana bread brownie ingredients
  • Granulated sugar: Adds sweet taste.
  • Sour cream: Adds moisture and makes these rich and delicious.
  • Butter: Your butter will need to be softened. Learn how to soften butter if you forgot to set it out!
  • Large eggs: Helps bind the banana brownies together.
  • Bananas: You will need three ripe bananas. These are the bananas that are brown and spotty!
  • Baking staples: All purpose flour, baking soda, salt and vanilla extract.
  • Chopped walnuts: Optional but recommended for added texture.
  • Brown butter frosting: Butter, brown sugar, milk, vanilla extract and confectioner’s sugar.

Substitutions and Variations

  • Fold chocolate chips into the batter for an extra sweet taste (use 1/2 to 1 cup).
  • White chocolate chips would make these similar to my favorite blondie recipe.
  • Swap walnuts for pecans.
  • Use Greek yogurt in place of sour cream to lighten it up a bit.
  • Add in a teaspoon of cinnamon.
  • Top with cream cheese frosting, sour cream frosting or even a coconut pecan frosting.
  • You can make these into thinner banana bars by using a larger 12×18″ baking sheet.

How to Make Banana Bread Brownies

A step by step photo collage of how to make banana bread brownies.
  • Mix wet ingredients: In a large mixing bowl, cream together sugar, sour cream, butter, and eggs until combined. Blend in bananas and vanilla extract.
  • Combine wet and dry ingredients: In separate bowl, whisk the flour, baking soda and salt together to remove lumps then add the flour to the banana mixture and gently mix until until just combined. Stir in walnuts if desired.
  • Bake: Spread batter evenly into prepared 13×9 pan and bake at 375 degrees for 20 to 25 minutes or until a toothpick comes clean when inserted in the center. Remove from oven to cool slightly.
  • Spread frosting on warm brownies: While brownies are baking prepare your brown butter frosting by heating butter in a large saucepan over medium heat. Add brown sugar and bring to a boil for two minutes. Remove from heat and add powdered sugar, vanilla and milk. Using a spatula, spread the brown butter frosting over warm brownies and top with chopped walnuts.

Brown Butter Frosting

I must admit, browning butter has been a baking fear of mine. Every bakers’ notes emphasize watching the butter closely because when it turns golden brown, it turns quickly. After learning how to make brown butter successfully, I can now tell you with full faith that it’s not so bad. Yes, you should watch the butter and stir it constantly, but it’s nothing to fret over!

Once the butter has browned, then you’ll mix it together with the remaining frosting ingredients until smooth. The consistency will be thinner (more like a glaze than a frosting to be honest), which makes it perfect for pouring over the warm bars. The frosting will thicken fast, so it’s important to move quickly!

banana bread brownies in baking sheet


How to tell if bananas are ripe?

The key to super moist, sweet and flavorful banana bread brownies is using bananas that have fully ripened. Your bananas should be covered in brown spots and soft to the touch. The riper the banana, the sweeter the brownies!

Can I use frozen bananas in baking?

Yes, it’s so easy to freeze bananas and it’s a great way to never toss a ripe banana again even if you don’t plan to bake with it right away. Just peel and slice your bananas then freeze in a single layer. Once frozen transfer to a freezer safe bag up to 3 months! When ready to use thaw and drain excess juices.


Once the brownies have cooled, store them in a covered container at room temperature. They will stay fresh for up to 3 days.

You may also freeze the brownies if you prefer. Flash freeze them first on a baking sheet for about an hour, then stack in a freezer container with a piece of parchment paper in between each layer. Let the brownies sit on the counter at room temperature for about an hour before serving.

banana bread brownies on plate with fork

More recipes we love with brown butter include these brown butter blondies, brown butter chocolate chip cookies and brown butter rice krispie treats!

More Recipes to Make with Ripe Bananas


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banana bread brownies on plate with fork

Banana Bread Brownies

5 from 5 votes
↑ Click stars to rate now!
Author: Jamielyn Nye
These banana bread brownies with brown butter frosting are nothing short of sinful! Made with ripe bananas and crunchy walnuts they're fluffy and moist with a rich frosting on top that makes them next level delicious!
Prep Time: 20 minutes
Cook Time: 20 minutes
Total Time: 40 minutes
Servings: 24



Brownie Batter:

  • 1 ½ cups granulated sugar
  • 1 cup sour cream
  • ½ cup butter , softened
  • 2 large eggs
  • 3 ripe bananas , mashed
  • 2 teaspoons vanilla extract
  • 2 cups all-purpose flour
  • 1 teaspoon baking soda
  • ¾ teaspoon table or fine sea salt
  • 1/2-1 cup chopped walnuts , you can omit if desired

Brown Butter Frosting:

  • ¼ cup butter
  • ¼ cup light brown sugar
  • 3 Tablespoons milk
  • 1 ½ teaspoons vanilla extract
  • 2 cups confectioner’s sugar


  • Heat oven to 375°F. Line a 9×13" pan with parchment paper, or grease and flour. Set aside.
  • In a large bowl, beat together sugar, sour cream, butter, and eggs until creamy. Blend in bananas and vanilla extract.
  • In separate bowl, whisk (or sift) the flour, baking soda and salt together.
  • Add the flour to the banana mixture and mix just until combined. Stir in walnuts if desired. Spread batter evenly into pan and bake for 20 to 25 minutes or until a toothpick comes clean.
  • Prepare the frosting as the brownies bake by heating butter in a large saucepan over medium heat. Add the brown sugar to the melted butter and bring to a boil, stirring continuously for about 2 minutes. Remove from heat immediately.
  • Add powdered sugar, vanilla extract and milk. Whisk together until smooth (it will be thinner than frosting). Using a spatula, spread the brown butter frosting over brownies. This is best done when both ingredients are warm. Sprinkle chopped walnuts on top if desired.
  • Slice brownies into 24 squares. Serve warm, room temperature or even cold!


  • Add chocolate chips to the batter before baking. Start with 1/2-1 cup.
  • Use Greek yogurt in place of sour cream. 
Storage: Allow brownies to cool and store in a covered container for 3 days.
Freezer Instructions: Place brownies on a baking sheet and freeze for 1 hour, or until hardened. Then place in a freezer container (you can stack with a piece of parchment paper in between each layer). Remove an hour before serving.


Calories: 257kcal | Carbohydrates: 37g | Protein: 2g | Fat: 11g | Saturated Fat: 5g | Cholesterol: 34mg | Sodium: 184mg | Potassium: 113mg | Sugar: 26g | Vitamin A: 270IU | Vitamin C: 1.4mg | Calcium: 27mg | Iron: 0.8mg

Nutrition provided is an estimate. It will vary based on specific ingredients used.

Course: Dessert
Cuisine: American

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