Delicious Banana Bread Brownies

Here is my favorite banana bread brownies recipe, with moist banana cake bars topped with a rich browned butter frosting, plenty of cinnamon, and crunchy walnuts throughout.

These banana bread brownies are what I make whenever I have overripe bananas sitting on my counter. They’re like banana bread and brownies had a baby – soft, sweet, and way too easy to eat straight from the pan. The browned butter frosting really makes them special, and my kids always ask me to make a double batch.

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What Kind of Bananas Should I Use?

The best bananas for this recipe are the ones sitting on your counter that are super ripe with lots of brown spots – or even completely brown. Those overripe bananas that you might think are past their prime are actually perfect for baking because they’re sweeter and mash up more easily. If your bananas aren’t quite ripe enough, you can speed up the process by putting them in a paper bag for a day or two, or if you’re in a hurry, bake them in their peels at 300°F for about 15-20 minutes until they turn black. Just make sure to let them cool before mashing, and you’ll have perfectly sweet bananas ready to go.

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Options for Substitutions

This recipe is pretty forgiving, so here are some swaps you can make if you need to:

• Sour cream: If you’re out of sour cream, Greek yogurt works perfectly as a 1:1 substitute. You can also use regular plain yogurt, though the texture might be slightly less rich.
• Butter: For the brownies themselves, you can swap butter with vegetable oil (use 3/4 cup instead of 1 cup). However, stick with butter for the frosting – it’s really what gives it that creamy texture.
• Bananas: The riper your bananas, the better! If you only have 3 bananas, that’s okay, but try to use 4 for the best banana flavor. You can’t really substitute bananas here since they’re the star of the show.
• All-purpose flour: Whole wheat flour can replace up to half of the all-purpose flour if you want a heartier texture. For a gluten-free version, use a 1:1 gluten-free baking flour blend.
• Walnuts: Not a fan of walnuts? Try pecans or chocolate chips instead. Or just leave them out completely – the brownies are great either way.
• Milk: Any milk works here – whole, 2%, almond, or oat milk. Start with 3 tablespoons and add more if needed to get your desired frosting consistency.

Watch Out for These Mistakes While Baking

The biggest mistake you can make with banana bread brownies is overbaking them, which turns these moist bars dry and cake-like – start checking at 20 minutes and pull them out when a toothpick comes out with just a few moist crumbs, not completely clean.

When browning the butter for the frosting, watch it like a hawk because it goes from perfectly nutty to burnt in seconds, and burnt butter will ruin your frosting with a bitter taste.

Make sure your bananas are super ripe with lots of brown spots, as underripe bananas won’t give you enough sweetness or moisture, leaving your brownies bland and dense.

For the smoothest frosting, let the browned butter cool for a few minutes before adding the powdered sugar, otherwise it can get grainy, and spread it on while the bars are still slightly warm so it melts into all the nooks and crannies.

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What to Serve With Banana Bread Brownies?

These brownies are pretty rich and sweet on their own, so they pair perfectly with a cold glass of milk or a hot cup of coffee. If you’re serving them for dessert after dinner, a scoop of vanilla ice cream on top takes them to the next level, especially if the brownies are still slightly warm. They also work great as an afternoon snack with some fresh berries on the side to balance out the sweetness. For a fun brunch spread, serve them alongside scrambled eggs and bacon – the salty-sweet combo is surprisingly good!

Storage Instructions

Store: Keep your banana bread brownies in an airtight container at room temperature for up to 3 days, or in the fridge for up to a week. The frosting stays nice and creamy either way, though I think they taste best at room temperature when the texture is perfectly soft.

Freeze: These freeze really well for up to 3 months. I like to cut them into individual squares and wrap each one in plastic wrap, then store them all together in a freezer bag. That way you can grab just one or two whenever a craving hits without thawing the whole batch.

Thaw: Just leave them on the counter for about 30 minutes to come to room temperature, or pop one in the microwave for 10-15 seconds if you can’t wait. The frosting softens up perfectly and they taste almost like they just came out of the oven.

Estimated Nutrition

Estimated nutrition for the whole recipe (without optional ingredients):

• Calories: 3900-4200
• Protein: 28-34 g
• Fat: 170-185 g
• Carbohydrates: 570-610 g

Ingredients

For the brownies:

• 1.25 cups sugar
• 1 cup sour cream (I prefer Daisy for a richer texture)
• 1/2 cup butter (softened to room temperature, about 70°F)
• 2 eggs
• 4 bananas (mashed until smooth with some small lumps)
• 2 tsp vanilla extract
• 2.25 cups all-purpose flour (I always use King Arthur for consistent results)
• 1 tsp baking soda
• 3/4 tsp salt
• 1/2 cup walnuts (chopped into 1/4-inch pieces)
• 1/2 tsp ground cinnamon

For the frosting:

• 1/2 cup butter (melted and browned until it smells nutty)
• 4 cups powdered sugar (sifted to remove any lumps)
• 1.5 tsp vanilla extract
• 4 tbsp milk

Step 1: Prepare Pan and Preheat Oven

Heat your oven to 375°F and grease a 9×13 inch baking pan with butter or cooking spray, making sure to coat the bottom and sides evenly.

This prevents sticking and ensures even browning on the edges.

Step 2: Cream Together Wet Ingredients

• 1/2 cup butter
• 1.25 cups sugar
• 1 cup sour cream
• 2 eggs

In a large mixing bowl, combine the softened butter, sugar, and sour cream, beating together until light and fluffy, about 2-3 minutes.

This incorporates air into the batter and creates a better texture.

Add the eggs one at a time, beating well after each addition to fully emulsify them into the mixture.

Step 3: Add Bananas and Vanilla

• 4 bananas
• 2 tsp vanilla extract

Stir the mashed bananas and 2 tsp vanilla extract into the wet mixture from Step 2 until well combined.

The bananas should be mashed smooth with just some small lumps remaining for texture—this prevents the brownies from becoming gluey.

Mix until you don’t see any streaks of banana.

Step 4: Combine Dry Ingredients and Fold into Batter

• 2.25 cups all-purpose flour
• 1 tsp baking soda
• 3/4 tsp salt
• 1/2 tsp ground cinnamon
• batter from Step 3
• 1/2 cup walnuts

In a separate bowl, whisk together the flour, baking soda, salt, and cinnamon.

Add this dry mixture to the banana mixture from Step 3 and mix gently for about 1 minute until just combined—don’t overmix, as this can make the brownies tough.

Fold in the chopped walnuts gently at the end.

I like to fold rather than stir here because it keeps the walnuts from breaking apart and distributes them more evenly throughout.

Step 5: Bake the Brownies

• batter from Step 4

Pour the batter from Step 4 into your prepared pan, spreading it evenly into the corners.

Bake in the preheated 375°F oven for 20-25 minutes, until a toothpick inserted in the center comes out with just a few moist crumbs.

The brownies should still be warm when you remove them from the oven—this is important for frosting them.

Step 6: Make Brown Butter Frosting

• 1/2 cup butter
• 4 cups powdered sugar
• 1.5 tsp vanilla extract
• 4 tbsp milk

While the brownies bake, melt the 1/2 cup butter in a saucepan over medium heat, then continue cooking, swirling occasionally, until it turns golden brown and smells nutty, about 5-8 minutes total.

Watch carefully to avoid burning.

Remove from heat and let cool for 2-3 minutes, then whisk in the sifted powdered sugar, 1.5 tsp vanilla extract, and milk until smooth and spreadable.

The frosting should be thick but pourable—if it’s too thick, add milk a teaspoon at a time.

Step 7: Frost and Cool

• baked brownies from Step 5
• frosting from Step 6

Spread the warm brown butter frosting from Step 6 evenly over the warm brownies from Step 5 immediately after removing them from the oven.

The warmth helps the frosting set slightly and adhere better.

Let cool completely at room temperature before cutting into squares and serving.

Delicious Banana Bread Brownies

Delicious Delicious Banana Bread Brownies recipe with step-by-step instructions.

Print Recipe Pin Recipe

Prep Time 15 minutes mins

Cook Time 25 minutes mins

Total Time 40 minutes mins

Servings 16 pieces

Calories 4050 kcal

Ingredients

  

For the brownies

• 1.25 cups sugar
• 1 cup sour cream (I prefer Daisy for a richer texture)
• 1/2 cup butter (softened to room temperature, about 70°F)
• 2 eggs
• 4 bananas (mashed until smooth with some small lumps)
• 2 tsp vanilla extract
• 2.25 cups all-purpose flour (I always use King Arthur for consistent results)
• 1 tsp baking soda
• 3/4 tsp salt
• 1/2 cup walnuts (chopped into 1/4-inch pieces)
• 1/2 tsp ground cinnamon

For the frosting

• 1/2 cup butter (melted and browned until it smells nutty)
• 4 cups powdered sugar (sifted to remove any lumps)
• 1.5 tsp vanilla extract
• 4 tbsp milk

Instructions

 

• Heat your oven to 375°F and grease a 9x13 inch baking pan with butter or cooking spray, making sure to coat the bottom and sides evenly. This prevents sticking and ensures even browning on the edges.
• In a large mixing bowl, combine the softened butter, sugar, and sour cream, beating together until light and fluffy, about 2-3 minutes. This incorporates air into the batter and creates a better texture. Add the eggs one at a time, beating well after each addition to fully emulsify them into the mixture.
• Stir the mashed bananas and 2 tsp vanilla extract into the wet mixture from Step 2 until well combined. The bananas should be mashed smooth with just some small lumps remaining for texture—this prevents the brownies from becoming gluey. Mix until you don't see any streaks of banana.
• In a separate bowl, whisk together the flour, baking soda, salt, and cinnamon. Add this dry mixture to the banana mixture from Step 3 and mix gently for about 1 minute until just combined—don't overmix, as this can make the brownies tough. Fold in the chopped walnuts gently at the end. I like to fold rather than stir here because it keeps the walnuts from breaking apart and distributes them more evenly throughout.
• Pour the batter from Step 4 into your prepared pan, spreading it evenly into the corners. Bake in the preheated 375°F oven for 20-25 minutes, until a toothpick inserted in the center comes out with just a few moist crumbs. The brownies should still be warm when you remove them from the oven—this is important for frosting them.
• While the brownies bake, melt the 1/2 cup butter in a saucepan over medium heat, then continue cooking, swirling occasionally, until it turns golden brown and smells nutty, about 5-8 minutes total. Watch carefully to avoid burning. Remove from heat and let cool for 2-3 minutes, then whisk in the sifted powdered sugar, 1.5 tsp vanilla extract, and milk until smooth and spreadable. The frosting should be thick but pourable—if it's too thick, add milk a teaspoon at a time.
• Spread the warm brown butter frosting from Step 6 evenly over the warm brownies from Step 5 immediately after removing them from the oven. The warmth helps the frosting set slightly and adhere better. Let cool completely at room temperature before cutting into squares and serving.