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Banana Cake with Browned Butter Rum Frosting

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This Banana Cake features a homemade banana cake covered in a sweet brown butter frosting with a touch of spiced rum, crunchy walnuts, and salted caramel drizzle. Serve for brunch or dessert, this is a perfect cake for any occasion.

Banana Cake with Rum Frosting

I made it a goal this year to share more cakes with you. I think cakes are a work of art and there are so many ways you can decorate a cake. While my style tends to be more rustic, I truly appreciate the nice, clean, buttoned-up look and I am constantly working on that skill.

In the meantime, there’s Banana Cake with Browned Butter Rum Frosting. This homemade banana cake is covered in a sweet brown butter frosting with a touch of spiced rum, walnuts, and salted caramel sauce.

The browned butter frosting brings out a nuttier taste which is the perfect complement to the banana cake, especially if you use walnuts or pecans in the cake. You might even consider lightly toasting the nuts.

An side view of a slice of banana cake and a cake stand blurred out in the background with frosting and caramel dripping down the side

Why You’ll Love It

If you’ve never tried browned butter frosting before, I am ready to knock your socks off. I’ve paired this frosting with zucchini cake and a butterscotch cake and each time I make the frosting, I am reminded just how special it is.

I happen to love banana-flavored baked goods including muffins, bread, and cakes. This banana cake is no exception, I don’t even need the frosting! The original recipe for this cake is adapted from some banana bars I found on Better Homes and Gardens.

The recipe for the banana bars did not need to be adjusted to turn this into a cake. I simply baked the cakes in two 8-inch round pans, but you can certainly use 9-inch pans as well.

Serving this as a cake makes it a great way to “fancy up” this dessert for baby showers, brunches, or birthdays, but if you prefer a single serving option, you can still make them as bars by following the original baking instructions.

A two layer banana cake with a couple bites missing, and a gold fork laying on the plate

The cake itself is a bit denser than your traditional cake, but the bananas and sour cream help keep it super moist. When you spread the batter in the pans, you may be concerned that it is not enough, but trust me it will bake up to be a nice thick layer of cake.

Whenever making a cake, I always recommend greasing the pans with Crisco spread and giving them a light coating of flour. I also prefer to line the bottom of my pan with parchment paper or silicone baking mats because it makes it so much easier to remove the cakes from the pans.

Tips for Browned Butter Frosting

The frosting is so easy! If you have never browned butter before, you are in for a treat! First, I recommend looking at my tutorial for how to brown butter which includes plenty of tips and an instructional video. It’s a simple process that transfers to the flavor of the butter.

For this frosting, you can prepare the brown butter ahead of time, or just allow for an extra 30 minutes for the butter to cool before making the frosting.

A white spatula with a dollop of brown butter frosting being held over the mixing bowl

If You Want to Brown the Butter Ahead of Time

  • You can place the brown butter in the refrigerators and leave until it reaches a solid state.
  • Then, you’ll simply melt the butter in the microwave for 30-60 seconds and stir it until it’s smooth. It won’t be completely melted, but just thick enough that you can get it nice and smooth.
Brown butter that has been melted and stirred in a white bowl

To Use the Brown Butter Right Away

  • Throw it in the freezer for 20-25 minutes. Part of the frosting will harden but part of it will stay soft or melted. Stir it all together until it’s completely smooth. Either way the butter is not a completely liquid state. 

To make the frosting, slowly add the powdered sugar and alternate in the liquid ingredients. Spend some time whipping the frosting for several minutes each time so you end up with a whipped, fluffy, and very spreadable frosting.

Two side by side images of brown butter, one is partially firm and one is whipped

How to Decorate This Cake

I was going for a bit of a more rustic look with this cake, so I did not level off (torte) the layers or worry about having that perfectly even frosting. Since it’s only two layers, as long as they are not lopsided, you don’t need to worry about having a super flat surface to stack the cake.

You’ll use about a third of the frosting in between the layers and the rest is used for covering the cake.

I also drizzled a swirl of salted caramel sauce and some chopped nuts in between the two layers on top for some added texture and sweetness. This is optional, especially if you have nuts in the cake, but I like the texture.

Two side by side photos frosting a cake and drizzling caramel

Seriously, I had no problem polishing off this slice of cake, and since my husband doesn’t love banana cake, I didn’t have to share! If you are looking for an alternative frosting, this would also be good with vanilla frosting or cream cheese frosting.

An overhead view of a cake frosting with a brown butter frosting showing the caramel swirl and chopped walnuts on top of the cake
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An overhead view of a slice of layered banana cake with frosting and caramel dripping down the side

Banana Cake with Browned Butter Rum Frosting

  • Author: Julianne Dell
  • Prep Time: 50 minutes
  • Cook Time: 22 minutes
  • Total Time: 1 hour 12 minutes
  • Yield: 10 slices

Description

This Banana Cake features a homemade banana cake covered in a sweet browned butter frosting with a touch of spiced rum, crunchy walnuts and salted caramel drizzle. Serve for brunch or dessert, this is a perfect cake for any occasion.

Ingredients

For the cake:

  • ½ cup (113g) butter, softened
  • 1 ⅓ cups (254g) granulated sugar
  • 1 ½ (5g) teaspoons baking powder
  • ½ teaspoon baking soda
  • ¼ teaspoon salt
  • 1 large egg
  • 1 cup (229g estimated) mashed ripe bananas (about 3 medium bananas)
  • ½ cup (118ml) light sour cream
  • 1 teaspoon (5ml) pure vanilla extract
  • 2 cups (280g) all-purpose flour
  • ¾ cup (87g) chopped walnuts  or pecans (optional)

For the frosting:

  • 10 tablespoons (143g) unsalted butter, browned
  • 34 cups (390-520g) powdered sugar
  • 1 teaspoon (5g) cinnamon
  • 12 tablespoons spiced rum (30ml) (optional- flavored as desired)
  • 34 tablespoons (59ml) milk
  • 2 teaspoons pure vanilla (10ml) extract
  • Salted caramel sauce (optional)
  • Walnuts or Pecans for garnish (optional)

Instructions

For the Cake:

  1. Preheat the oven to 350°F. Grease two 8-inch baking pans and line with parchment paper or a silicone mat; set aside.
  2. In a large mixing bowl beat butter with an electric mixer on medium speed for about 30 seconds.
  3. Next add the sugar, baking powder, baking soda, and salt. Beat until all ingredients are combined, scraping sides of bowl as needed.
  4. Beat in the egg, mashed bananas, sour cream, and vanilla until mix until combined.
  5. Next, add the flour and walnuts, beating as much as you can using the mixer, but being careful not to overmix. Then use a wooden spoon or spatula and, stir in any remaining flour and the walnuts.
  6. Pour the batter into the prepared baking pans, spreading evenly. Bake in a 350°F for 20-25 minutes. Test the cake for doneness by inserting a toothpick into the center of the cake. If the toothpick comes out clean, your cake is done. Cool completely.

For the Frosting:

  1. To brown the butter, use a small saucepan, and cut the butter into pieces. Melt the butter over medium heat and allow it to boil and bubble. Once it starts boiling, stir it frequently and it will slowly start to turn an amber color and releases a nutty aroma. Remove the butter from the heat and place in the freezer for 20-25 minutes and then stir until smooth.
  2. Slowly add the powdered sugar 1 cup at a time, alternating in some of the liquid ingredients (Rum, milk and vanilla). The frosting will be thick at times, but as you slowly add the liquid, it will become smoother. Beat the frosting each time you add the powdered sugar until the frosting is completely smooth, whipped and fluffy.
  3. Spread 1/3 of the frosting on top of the first layer, and drizzle some caramel and chopped nuts if desired. Then spread the remaining frosting over the cooled cake. Garnish with caramel and walnuts. Store in an airtight container.

Notes

  • The original cake recipe is from Better Homes and Gardens.
  • This can also be made in a 9-inch pan and reduce the bake time 3-5 minutes.
  • For more tips about brown butter, see my how-to post.
  • If you’d like to prepare the browned butter ahead of time (up to 3 days), you can place the butter in the refrigerator and leave it until it reaches a solid state. Then, you’ll simply melt the butter in the microwave for 30-60 seconds and stir it until it’s smooth. It won’t be completely melted, but just thick enough that you can get it nice and smooth.
  • Substitutes for Rum: The rum in the frosting is optional. To omit, sub with additional milk. You should need 2-4 tablespoons of liquid to achieve the right consistency for the frosting. Spiced rum is best.
  • Substitutes for sour cream: You can use plain or Greek yogurt.
  • Toast the Nuts: For added flavor, lightly toast the nuts for 5-10 minutes prior to adding them to the cake.
Nutrition Information:
1 slice
768
100 g
145mg
28.9g
14.7g
124.2g
2g
6g
77.7mg
  • Category: Cake
  • Method: Baked
  • Cuisine: American

Keywords: Banana Cake, Brown Butter Frosting, Cakes with Bananas

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