These tender banana bread bars are enriched with the deep, nutty flavor of brown butter—both in the batter and in the silky frosting. They bake up soft, moist, and aromatic, making them a beautiful dessert to share with family, friends, or any crowd.
Why You’ll Love This Recipe
These bars take everything you love about banana bread and elevate it with rich brown butter. They come together quickly, use simple ingredients, and deliver a bakery-quality treat with minimal effort. The frosting melts ever so slightly into the warm bars, creating a soft, luscious finish that makes each bite irresistible.
Ingredients
(Tip: You’ll find the full list of ingredients and measurements in the recipe card below.)
Banana Bread Bars
1/2 cup (110g) unsalted butter, browned
1 cup (200g) granulated sugar
1/2 cup (105g) light brown sugar, packed
2 large eggs
1 cup (250g) sour cream
1 1/2 cups (385g) ripe bananas, mashed
1 tsp vanilla extract
1 tsp baking soda
1/2 tsp kosher salt
2 cups (265g) all-purpose flour
Brown Butter Frosting
3/4 cup (170g) unsalted butter, browned
2 tbsp unsalted butter, chilled
3 cups (300g) powdered sugar
1 tsp vanilla extract
1/4 cup (60g) milk, room temperature
Directions
Preheat the oven to 350°F and grease an 11×15 jelly roll pan.
Combine the butter for both the bars and the frosting (1 1/4 cups total, reserving the extra 2 tbsp separately) in a saucepan. Melt over medium heat and continue cooking until it becomes foamy, quiet, and turns light amber.
Measure 1/2 cup of the browned butter for the banana bars and place it in a mixing bowl.
Pour the remaining browned butter into another mixing bowl and stir in the chilled 2 tbsp butter to help it cool. Refrigerate this bowl until the butter solidifies for the frosting.
For the bars, whisk the granulated sugar and brown sugar into the 1/2 cup brown butter.
Add the eggs and whisk well.
Mix in the sour cream, mashed bananas, and vanilla extract.
Whisk in the baking soda and salt, then gently fold in the flour until combined.
Spread the batter evenly into the prepared pan and bake for 25–30 minutes.
While the bars cool slightly, prepare the frosting.
In a mixing bowl, beat the chilled solid brown butter until creamy. Gradually mix in the powdered sugar, then add the vanilla and milk until smooth.
Spread the frosting over the warm bars and allow them to cool for about 30 minutes before slicing.
Servings and timing
This recipe makes approximately 20–24 bars when baked in an 11×15 jelly roll pan.
Prep time: 20 minutes
Cook time: 25 minutes
Cooling time: 30 minutes
Variations
• Add chocolate chips for a richer, sweeter bar.
• Fold in toasted walnuts for added texture and nuttiness.
• Add a pinch of cinnamon or nutmeg to the batter for warm spice.
• Use coconut sugar in place of brown sugar for a deeper caramel flavor.
• Swap part of the milk in the frosting with cream for an even richer finish.
Storage/Reheating
Store the cooled bars in an airtight container at room temperature for up to 2 days. For longer storage, refrigerate for up to 1 week. To serve, allow refrigerated bars to come to room temperature for the softest texture. These bars can also be frozen (unfrosted or frosted) for up to 2 months; thaw in the refrigerator before serving.
FAQs
How do I know the brown butter is ready?
It should be golden amber with brown specks at the bottom and have a nutty aroma.
Can I bake this in a 9×13 pan?
Yes. Add about 5 extra minutes to the bake time and check the center for doneness.
What if I don’t have enough bananas?
If you’re slightly short of 1 1/2 cups, you can make up the difference with applesauce.
Can I make these bars gluten free?
Yes, a cup-for-cup gluten free baking flour typically works well.
Can I make the bars without frosting?
Absolutely. They are delicious on their own, though the frosting adds extra richness.
Can I make them ahead of time?
Yes. Bake and frost the bars, then store covered. They stay fresh for several days.
Can I halve the recipe?
Yes. Bake in an 8×8 pan for about 20 minutes.
Why must the brown butter cool for the frosting?
The butter needs to solidify slightly to whip properly and create a smooth frosting.
Can I use Greek yogurt instead of sour cream?
Yes, full-fat Greek yogurt makes a suitable substitute.
How should I slice the bars for clean edges?
Allow the bars to cool fully, then use a sharp knife wiped clean between cuts.
Conclusion
These brown butter frosted banana bread bars offer the perfect blend of simplicity and indulgence. With rich brown butter woven into every layer, they deliver a soft, flavorful treat ideal for gatherings or everyday baking. Easy to prepare and impossible to resist, this recipe is sure to become a favorite in your dessert rotation.
These Brown Butter Frosted Banana Bread Bars are soft, moist, and packed with rich, nutty flavor from brown butter. Finished with a silky frosting that melts into the warm bars, they make the perfect treat for sharing or indulging at home.
Ingredients
Banana Bread Bars:
1/2 cup (110g) unsalted butter, browned
1 cup (200g) granulated sugar
1/2 cup (105g) light brown sugar, packed
2 large eggs
1 cup (250g) sour cream
1 1/2 cups (385g) ripe bananas, mashed
1 tsp vanilla extract
1 tsp baking soda
1/2 tsp kosher salt
2 cups (265g) all-purpose flour
Brown Butter Frosting:
3/4 cup (170g) unsalted butter, browned
2 tbsp unsalted butter, chilled
3 cups (300g) powdered sugar
1 tsp vanilla extract
1/4 cup (60g) milk, room temperature
Instructions
Preheat oven to 350°F (175°C). Grease an 11×15 jelly roll pan.
Brown the butter for both the bars and frosting (total 1 1/4 cups). Pour 1/2 cup into a bowl for the banana bars. Place the remaining brown butter into another bowl and stir in the 2 tbsp chilled butter. Refrigerate until solid for frosting.
In the banana bar bowl, whisk in the granulated and brown sugars. Add eggs and mix well.
Stir in sour cream, mashed bananas, and vanilla extract.
Add baking soda and salt, then fold in flour just until combined.
Spread batter evenly into prepared pan and bake for 25–30 minutes, until a toothpick inserted in the center comes out clean.
While bars cool slightly, beat the solidified brown butter for frosting until creamy. Gradually mix in powdered sugar, then add vanilla and milk until smooth and spreadable.
Spread frosting over warm bars. Let cool for about 30 minutes before slicing and serving.
Notes
Use a light-colored pan to better monitor browning of the butter.
Bars can be made ahead and refrigerated or frozen.
Greek yogurt may be used instead of sour cream.
Add cinnamon or nutmeg for extra warmth and depth.
Let bars cool completely before slicing for clean edges.
