Banana Bread Brownies (Soft Banana Bars with Frosting)

These soft and moist banana bread brownies (also called banana bars) taste like a cross between fluffy banana bread and a tender sheet cake. Made with ripe bananas and sour cream, they are topped with a sweet brown butter-style vanilla frosting poured over the warm bars. This easy 9×13 banana dessert is perfect for using up overripe bananas, feeding a crowd, potlucks and bake sales.

Prep Time: 15 minutes | Bake Time: 25–30 minutes | Total Time: 45 minutes plus cooling | Yield: 24 squares | Oven: 350°F (175°C)

Why You’ll Love Banana Bread Brownies

• The best way to use ripe bananas: 3 bananas go into one pan.
• Super soft and moist thanks to sour cream.
• Easy one-bowl batter with no mixer required.
• Feeds a crowd: one 9×13 pan makes 24 squares.

Ingredients

For the Banana Brownies

• 2 large eggs
• 3 ripe bananas, mashed (about 1 1/2 cups)
• 1 1/2 cups (300 g) granulated sugar
• 1 cup (240 g) sour cream
• 1/2 cup (113 g) butter, softened
• 2 cups (250 g) all-purpose flour
• 1 teaspoon baking soda
• 1/2 teaspoon salt
• 1 teaspoon vanilla extract

For the Frosting

• 1/2 cup (113 g) butter
• 3 cups (360 g) powdered sugar
• 1 teaspoon vanilla extract
• 3 tablespoons milk, or as needed
• 1/4 teaspoon ground cinnamon (optional)

How to Make Banana Bread Brownies

1. Preheat. Heat the oven to 350°F (175°C). Grease a 9×13-inch (23×33 cm) baking pan.
2. Mix the wet ingredients. In a large bowl, beat the eggs, mashed bananas, sugar, sour cream, softened butter and vanilla until combined.
3. Add the dry ingredients. Stir in the flour, baking soda and salt just until combined. Do not overmix.
4. Bake. Spread the batter evenly in the pan and bake for 25–30 minutes, until a toothpick inserted in the center comes out clean.
5. Make the frosting. Melt the butter in a saucepan (let it turn lightly golden for a nutty brown butter flavor). Remove from the heat and stir in the powdered sugar, vanilla, cinnamon if using, and enough milk to make a smooth, spreadable frosting.
6. Frost. Spread the frosting over the warm bars. It will melt slightly and then set.
7. Cool and serve. Let the bars cool completely before cutting into squares.

Tips for the Best Banana Bars

• Use very ripe bananas with lots of brown spots for the sweetest flavor and extra moisture.
• Don’t overmix after adding the flour, or the bars will be tough.
• Check early. Start testing at 25 minutes so the bars stay soft and moist.
• Frost while warm for a smooth, glossy frosting layer.

Easy Variations

• Cream cheese frosting: Beat 4 oz softened cream cheese with 1/4 cup butter, 2 cups powdered sugar and 1 teaspoon vanilla.
• Add-ins: Fold 1 cup chocolate chips or chopped walnuts into the batter.
• No sour cream? Use the same amount of plain Greek yogurt.

How to Store and Freeze

Store the bars covered at room temperature for up to 2 days, or in the refrigerator for up to 5 days. Freeze unfrosted or frosted squares, well wrapped, for up to 3 months.

Frequently Asked Questions

Are banana bread brownies the same as banana bars?

Yes. They are soft, cake-like banana bars baked in a sheet pan, not fudgy chocolate brownies.

Can I make them in a smaller pan?

Halve the recipe and bake it in an 8×8-inch pan for about 25 minutes.

Can I use frozen bananas?

Yes. Thaw them completely and include the liquid that comes out of them.

More Easy Desserts to Try

• German Chocolate Brownies
• Cinnamon Roll Poke Cake
• Kentucky Butter Pound Cake
• Pumpkin Cream Cheese Bundt Cake