Moist Banana Cake with Brown Butter Frosting

This banana cake has a tender crumb and honest banana flavor, topped with a brown butter frosting that tastes toasty and rich.

The cake comes together quickly in one bowl, and browning the butter for the frosting adds a caramel-like depth a plain buttercream just can’t match.

What Makes This Banana Cake So Good

A full cup of mashed banana and a good spoonful of sour cream keep the cake soft for days. No dry edges here, just a fine, even crumb.

The frosting is where the toasty character comes from. You melt the butter until the milk solids turn amber and smell nutty, then whip it into a creamy frosting with a deep caramel note.

Ingredients

For the cake:

• 1/2 cup unsalted butter, melted and cooled slightly: melted butter makes mixing fast and keeps the crumb tender.
• 1 cup granulated sugar: sweetness that lets the banana come through.
• 1/2 cup packed light brown sugar: adds a subtle molasses warmth.
• 2 large eggs, at room temperature: helps the batter emulsify smoothly.
• 1 cup mashed very ripe banana: (about 2 large bananas): the skin should have lots of brown spots.
• 1/2 cup full-fat sour cream: guarantees a moist crumb; Greek yogurt works too.
• 2 tsp vanilla extract: rounds out the flavor.
• 2 cups all-purpose flour: spoon and level to avoid a dense cake.
• 1 tsp baking soda: the lift for this quick bread style cake.
• 1/2 tsp salt: balances all the sweetness.

For the brown butter frosting:

• 1 cup unsalted butter: you’ll brown this butter for the frosting.
• 3 1/2 cups powdered sugar: sifted if it’s lumpy.
• 2 to 3 tbsp heavy cream: thins the frosting to a spreadable texture.
• 1 tsp vanilla extract.
• Pinch of salt.

Variations / Substitutions

• Swap sour cream for full-fat Greek yogurt: the cake will be just as moist.
• Add 1/2 cup toasted chopped pecans: fold them into the batter or sprinkle on top of the frosting for crunch.
• Use regular butter instead of brown butter: you’ll get a classic vanilla frosting, still delicious.
• Make it gluten-free: use a 1:1 gluten-free flour blend in place of the all-purpose flour.

If you love this, try our classic banana bread recipe next.

How to Make Moist Banana Cake with Brown Butter Frosting

Step 1: Brown the Butter for the Frosting

Place the 1 cup butter in a small saucepan over medium heat. Melt it completely, then keep cooking, swirling the pan every 30 seconds or so. After about 5 to 7 minutes the butter will foam, the milk solids on the bottom will turn golden brown, and you’ll smell a nutty, toasty aroma.

Pour the browned butter into a heatproof bowl right away, scraping all those brown bits in. Let it cool at room temperature until it’s solid but still soft, like the consistency of room temperature butter. This takes about 1 hour, or you can pop it in the fridge and stir every 10 minutes to speed it up.

Don’t walk away while the butter is on the stove. It goes from beautifully brown to burnt in seconds, so keep an eye on it.

Step 2: Mix the Batter

Preheat your oven to 350°F (175°C) and grease a 9×13-inch baking pan. In a medium bowl, whisk the 2 cups flour, 1 tsp baking soda, and 1/2 tsp salt.

In a large bowl, whisk the 1/2 cup melted butter, 1 cup granulated sugar, and 1/2 cup brown sugar until well combined. Add the 2 eggs, 1 cup mashed banana, 1/2 cup sour cream, and 2 tsp vanilla and whisk until smooth. Pour the dry ingredients into the wet and stir gently with a spatula just until no dry streaks remain. A few small lumps are fine.

The batter will be thick and pale with golden flecks. Overmixing at this stage makes the cake tough, so stop as soon as the flour disappears.

Step 3: Bake the Cake

Scrape the batter into the prepared pan and spread it evenly with the spatula. Bake on the middle rack for 28 to 32 minutes, until the top is golden and a toothpick inserted in the center comes out clean or with a few moist crumbs.

Let the cake cool completely in the pan set on a wire rack. The edges will pull away slightly, and the top will feel springy when you press it lightly.

Step 4: Whip the Frosting

Once the brown butter has reached the consistency of softened butter (not melty), put it in a large bowl. Beat it with an electric mixer on medium speed until smooth and creamy, about 1 minute. Gradually sift in the 3 1/2 cups powdered sugar, then add 1 tsp vanilla, a pinch of salt, and 2 tbsp heavy cream.

Beat on low until the sugar is moistened, then increase to medium-high and whip for 2 to 3 minutes, scraping the bowl once or twice. The frosting should be fluffy and spreadable but hold its shape. If it feels too stiff, add the remaining tablespoon of cream; if it’s too thin, beat in a little extra powdered sugar.

Step 5: Frost the Cake and Slice

Spread the frosting over the fully cooled cake with an offset spatula, working it to the edges. Swirl the top for a rustic look. Slice into 12 squares and serve right away, or cover and chill.

The banana flavor deepens overnight, so leftovers will taste even better the next day.

Tips for the Best Banana Cake

• Bring cold ingredients to room temperature. Cold eggs or sour cream can make the butter seize up and give you a lumpy batter.
• Cool the cake completely before frosting. Even a little warmth will melt the brown butter and turn your frosting into a soupy mess.
• For a deeper nutty note, let the butter brown until the specks are a dark amber and the aroma smells profoundly toasty, but pull it off the heat the second it’s ready.

Bake times by pan:

Keeping Banana Cake Fresh

• Refrigerate: Cover the cake tightly and store in the fridge for up to 4 days. The frosting will stay firm and the cake stays moist.
• Serve cold: This cake is excellent straight from the fridge, which makes it a handy make-ahead dessert.

Frequently Asked Questions

Can I use frozen bananas?

Yes, thaw them completely and drain off any liquid before mashing. Measure out 1 cup for the recipe.

My frosting turned out grainy. What went wrong?

The butter likely wasn’t browned long enough to fully melt the milk solids, or the powdered sugar wasn’t sifted. Sift the sugar and beat the frosting until completely smooth.

Can I make this as a layer cake?

Absolutely, divide the batter between two greased 9-inch round pans and bake for 25 to 28 minutes. Double the frosting if you plan to fill and cover the sides.

Banana Cake with Brown Butter Frosting Recipe

Print Recipe Pin Recipe

Prep Time 25 minutes mins

Cook Time 30 minutes mins

Total Time 55 minutes mins

Servings: 12 servings

Calories: 480

Ingredients Method Notes

Ingredients

  

• 1/2 cup unsalted butter, melted and cooled slightly
• 1 cup granulated sugar
• 1/2 cup packed light brown sugar
• 2 large eggs, at room temperature
• 1 cup mashed very ripe banana (about 2 large bananas)
• 1/2 cup full-fat sour cream
• 2 tsp vanilla extract
• 2 cups all-purpose flour
• 1 tsp baking soda
• 1/2 tsp salt
• 1 cup unsalted butter
• 3 1/2 cups powdered sugar
• 2 to 3 tbsp heavy cream
• 1 tsp vanilla extract
• Pinch of salt

Method

 

1. Brown the 1 cup butter in a saucepan over medium heat until golden and nutty, about 5 to 7 minutes. Pour into a bowl and cool until solid but soft.
2. Preheat oven to 350°F (175°C). Grease a 9×13-inch pan. Whisk flour, baking soda, and salt. In a large bowl, whisk melted butter, sugars, eggs, banana, sour cream, and vanilla. Stir in dry ingredients until just combined.
3. Pour batter into pan, spread even, and bake 28 to 32 minutes until a toothpick comes out clean. Cool completely.
4. Beat the cooled brown butter until creamy. Sift in powdered sugar, then add vanilla, salt, and 2 tbsp cream. Whip until fluffy, adding more cream if needed.
5. Spread frosting over the cooled cake, slice, and serve.

Notes

Allow the brown butter to cool and solidify for about 1 hour before making the frosting, or chill and stir to hurry it along. The cake gets even better after a night in the fridge.