Home Desserts Banana Bread Bars with Brown Butter Frosting

Banana Bread Bars with Brown Butter Frosting

These banana bread bars with brown butter frosting have all the cozy flavors of banana bread but in thick, portable bar form.

The bars themselves are super moist from the mashed bananas and sour cream. But the real star is the nutty, caramelized frosting poured over the warm bars. It’s like the lovechild of banana bread and a cinnamon roll. 

I love these babies for breakfast, an anytime snack, or a simple dessert. I can’t stop making them!

A slice of Banana Bread with Brown Butter Frosting served on a white blue vintage design plate served on a wooden table.
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Why You’ll Love These Banana Bread Bars with Brown Butter Frosting

Decadent Flavor: The combination of ripe bananas, brown butter, and vanilla creates an irresistible flavor profile.

Tender and Creamy Texture: With a moist and tender crumb from the bananas, and a luscious, creamy frosting, these bars offer a delightful texture.

Crowd-Pleaser: Perfect for any gathering, these bars will be a hit with their decadent taste and beautiful presentation.

Comfort Food: They’re reminiscent of classic banana bread but elevated with the rich brown butter frosting.

A square slice of Banana Bread with Brown Butter Frosting garnished with a slice of banana on top.

Ingredients

  • Granulated Sugar: It adds the perfect amount of sweetness to balance the rich, nutty notes of brown butter.
  • Sour Cream: The secret to incredibly tender and moist banana bars.
  • Unsalted Butter: It’s browned to perfection for a deep, toasty flavor.
  • Large Eggs: They act as a binding agent and contribute to the soft, fluffy texture.
  • Mashed Ripe Bananas: The star ingredient provides natural sweetness, moisture, and classic banana bread flavor. The riper, the better!
  • Vanilla Extract: It enhances all the flavors and adds a subtle, sweet aroma.
  • All-Purpose Flour and Baking Soda: The dynamic duo creates the perfect crumb and helps the bars rise beautifully.
  • Salt: Just a pinch intensifies the sweet and nutty flavors in each bite.
  • Chopped Walnuts (optional): For added crunch and texture to complement the soft, tender bars.
  • Powdered Sugar and Milk: They create a decadent, silky-smooth frosting for the perfect finishing touch.
Banana Bread with Brown Butter Frosting slice served on a white blue plate, glass of milk next to it.

How to Make Banana Bread Bars with Brown Butter Frosting

These bars are just as easy as traditional banana bread!

1. Prep the oven and pan. Set to 375°F. Grease and flour a 15×10-inch jelly roll pan or line with parchment paper. For thicker bars, use a 9×13-inch pan and increase baking time by 5-10 minutes.

2. Mix the wet ingredients. In a large bowl, beat together the sugar, sour cream, softened butter, and eggs until creamy. Blend in the mashed bananas and vanilla extract.

3. Combine the dry ingredients. In a separate bowl, whisk together the flour, baking soda, and salt. Gradually stir the dry ingredients into the wet ingredients until just combined. Fold in the chopped walnuts if using.

4. Bake the bars. Spread the batter evenly into the prepared pan. Bake for 20-25 minutes, until golden brown and a toothpick inserted into the center comes out clean.

5. Brown the butter. Heat the butter in a saucepan over medium heat past the melting point until it boils and turns a delicate brown color. Watch carefully and stir often to prevent burning.

6. Make the frosting. Remove the butter from the heat and immediately add the powdered sugar, vanilla, and milk. Whisk until smooth. Adjust the consistency with more powdered sugar or milk as needed.

7. Cool and frost. Remove the bars from the oven and let cool slightly until just warm to the touch. Spread the brown butter frosting evenly over the top of the warm bars.

8. Serve. Allow the bars to cool completely before cutting and serving. Enjoy!

Top view of a slice of banana bread with brown butter frosting served on a  plate and a glass of milk next to it.

Tips for the Best Banana Bread Bars with Brown Butter Frosting

These tips will make your bars absolutely irresistible!

  • The riper, the better. Use overripe bananas for maximum sweetness and banana flavor. The browner and spottier, the better!
  • Room temperature is key. Bring ingredients like butter, eggs, and sour cream to room temperature before mixing. This ensures a smooth, evenly mixed batter.
  • Avoid overmixing! Mix the wet and dry ingredients until just combined. Overmixing can lead to tough, rubbery bars.
  • Keep a watchful eye. As you brown the butter for the frosting, stirring constantly, keep a close eye on it. It can go from browned to burnt very quickly.
  • Try a warm trick. Spread the brown butter frosting onto the bars while they’re still slightly warm. This allows the frosting to spread easily and soak in a bit.
  • Add optional mix-ins. Customize the bars by folding in up to 1 cup of mix-ins, such as chocolate chips, chopped nuts, or dried fruit.
Banana bread with brown butter frosting slice on a wooden chopping board.

How to Store

Follow these steps to keep leftover bars fresh.

To Store: Store leftovers in an air-tight container at room temperature for 3-4 days or in the refrigerator for up to a week. The brown butter frosting may start to lose its consistency after a few days in the fridge.

To Freeze: For best results, freeze the unfrosted banana bread bars tightly wrapped in plastic wrap or aluminum foil for up to 3 months. Frost the bars after thawing for maximum freshness.

More Banana Desserts You Have to Try

The Best Banana Cake
Banana Blueberry Muffins
Double Chocolate Banana Bread
Banana Mug Cake

Banana Bread Bars with Brown Butter Frosting

Course: DessertsCuisine: American
Servings

12

servings
Prep time

15

minutes
Cooking time

20

minutes
Calories

531

kcal

These decadent banana bread bars with brown butter frosting are moist, sweet, and perfect for any occasion! You’ll love them!

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Ingredients

  • For the Banana Bread Bars:
  • 1 1/2 cups granulated sugar

  • 1 cup sour cream (can substitute with plain Greek yogurt)

  • 1/2 cup unsalted butter, softened

  • 2 large eggs

  • 1 3/4 cups mashed ripe bananas (about 3-4 bananas)

  • 2 teaspoons vanilla extract

  • 2 cups all-purpose flour

  • 1 teaspoon baking soda

  • 3/4 teaspoon salt

  • 1/2 cup chopped walnuts (optional)

  • For the Brown Butter Frosting:
  • 1/2 cup unsalted butter

  • 2-4 cups powdered sugar

  • 1 teaspoon vanilla extract

  • 2-3 tablespoons milk or half-and-half

Instructions

  • Preheat the oven to 375°F. Grease and flour a 15×10-inch jelly roll pan or line it with parchment paper. For thicker bars, use a 9×13-inch pan and increase the baking time by 5-10 minutes.
  • In a large bowl, beat together the sugar, sour cream, softened butter, and eggs until creamy. Blend in the mashed bananas and vanilla extract.
  • In a separate bowl, whisk together the flour, baking soda, and salt. Gradually stir the dry ingredients into the wet ingredients until just combined. Fold in the chopped walnuts, if using.
  • Spread the batter evenly into the prepared pan. Bake for 20-25 minutes, until golden brown and a toothpick inserted into the center comes out clean.
  • While the bars bake, make the brown butter frosting. Heat the butter in a saucepan over medium heat past the melting point until it boils and turns a delicate brown color. Watch carefully and stir often to prevent burning.
  • Remove the butter from the heat and immediately add the powdered sugar, vanilla, and milk. Whisk until smooth. Add more powdered sugar or milk as needed to reach desired consistency – it should be thicker than a glaze but thinner than frosting.
  • Remove the bars from the oven and let cool slightly until just warm to the touch. Spread the brown butter frosting evenly over the top of the warm bars.
  • Allow the bars to cool completely before cutting and serving. Store leftovers in an airtight container at room temperature for 3-4 days or in the refrigerator for up to a week.

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author avatar
Kim - InsanelyGood
Hey there! I'm Kim. I love running, cooking, and curling up with a good book! I share recipes for people who LOVE good food, but want to keep things simple :)

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