This chocolate banana layer cake stacks two moist cocoa layers made with ripe bananas under a thick, fudgy chocolate buttercream.
Buttermilk and oil keep the crumb soft for days, and the bananas add natural sweetness without a strong fruit flavor. It is a showstopper for birthdays but simple enough for a weekend bake.
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Why This Chocolate Banana Layer Cake Recipe Works
Very ripe bananas bring moisture and sweetness, so the cake needs less oil than many chocolate cakes. The speckled peel is the sign that the fruit is ready to mash.
Natural cocoa reacts with the baking soda and buttermilk for a good rise and a deep chocolate flavor. Combining the wet ingredients first makes the batter smooth in a few stirs.
The frosting uses butter, powdered sugar, and more cocoa, with cream to loosen it to a spreadable texture. A little salt keeps the sweetness from tasting flat.
Ingredients for Chocolate Banana Layer Cake
- 3 very ripe bananas, mashed, about 1 1/2 cups
- 2 cups all purpose flour
- 1 1/2 cups natural unsweetened cocoa powder, 3/4 cup for the cake and 3/4 cup for the frosting
- 2 teaspoons baking soda
- 1 teaspoon baking powder
- 1/2 teaspoon salt, plus a pinch for the frosting
- 2 large eggs
- 1 cup buttermilk
- 1/2 cup vegetable oil
- 3 teaspoons vanilla extract, 1 for the cake and 2 for the frosting
- 1 1/2 cups granulated sugar
- 1 cup unsalted butter, softened
- 3 1/2 cups powdered sugar
- 1/2 cup heavy cream
Bananas. Mash them until mostly smooth, and use fruit with a heavily speckled peel for the sweetest flavor.
Natural cocoa. Use natural cocoa rather than Dutch process, since the cake relies on baking soda to rise.
Buttermilk. If you have none, stir 1 tablespoon of vinegar or lemon juice into 1 cup of milk and let it sit for 5 to 10 minutes.
Butter. Soften it until it dents under a finger so it whips into a smooth, fluffy frosting.
Heavy cream. Add a splash more if the frosting feels too stiff to spread.
How to Make Chocolate Banana Layer Cake
1. Prep the pans Heat the oven to 350 degrees F and grease two 9 inch round pans. Line the bottoms with parchment paper.
2. Whisk the dry mix Whisk the flour, 3/4 cup of the cocoa, baking soda, baking powder, and salt in a bowl. Set it aside.
3. Mix the wet batter Beat the eggs, sugar, buttermilk, oil, and 1 teaspoon of the vanilla in a large bowl until smooth. Stir in the mashed bananas.
4. Combine Mix the dry ingredients into the wet ingredients until just combined. Divide the batter evenly between the pans.
5. Bake Bake for 30 to 35 minutes until a toothpick comes out clean or with a few moist crumbs. Cool in the pans for 10 minutes, then cool completely on a rack for about 1 hour.
6. Make the frosting Beat the butter for 2 to 3 minutes until fluffy. Add the powdered sugar and remaining cocoa, then the cream, 2 teaspoons vanilla, and a pinch of salt, and beat until creamy.
7. Stack the layers Trim the tops if they have domed so the layers sit flat. Spread frosting on the first layer, add the second, and frost the top and sides.
8. Finish Add chocolate shavings if you like and let the cake sit for 30 minutes before slicing. Add banana slices right before serving.
How to Serve Chocolate Banana Layer Cake
Slice the cake with a hot, clean knife and serve it at cool room temperature. Pair it with caramel coffee frappe or cookies and cream frappe for a cold drink. Add malted milk toffee crunch ice cream and dark chocolate mousse for a rich dessert plate.
How to Store and Reheat Chocolate Banana Layer Cake
Keep the frosted cake covered at cool room temperature for up to 2 days, or refrigerate it for up to 5 days. Let chilled slices sit at room temperature for about 30 minutes before serving. Freeze unfrosted layers wrapped tightly for up to 3 months.
Tips and Variations for Chocolate Banana Layer Cake
Use natural cocoa. Dutch process cocoa will not react with the baking soda the same way.
Measure flour correctly. Spoon flour into the cup and level it off so the cake stays moist.
Trim the domes. Leveling the tops makes the layers stack neatly.
Cool completely. Warm layers melt the frosting, so wait until they are cool.
Flag the allergens. This cake contains wheat, eggs, and milk, so label it for guests with allergies.
Skip the raw batter. The batter contains raw eggs and flour, so do not taste it before baking.
Add bananas last. Banana slices brown quickly, so add them right before serving.
Check trusted guidance. For general advice on baking with eggs safely, read the University of Wisconsin Extension leftovers guidance.
Frequently Asked Questions About Chocolate Banana Layer Cake
Can I make chocolate banana layer cake ahead of time?
Yes, bake and wrap the layers a day ahead and frost on the day you serve. Frosted cake also keeps well in the refrigerator.
How ripe should bananas be for chocolate banana layer cake?
Use bananas with a heavily speckled peel, because they are sweeter and mash more easily. Underripe bananas leave the cake dry and bland.
Can I freeze chocolate banana layer cake?
Yes, freeze the unfrosted layers wrapped tightly for up to 3 months. Thaw them overnight before frosting.
Can I use whole wheat flour?
You can replace up to half of the flour with whole wheat flour. The cake will be slightly denser.
Can I bake it in a different pan?
Use a 9×13 inch pan for a sheet cake and bake until a toothpick comes out clean. Start checking earlier than the layer cake time.
Double Chocolate Banana Layer Cake
Equipment
- Two 9 inch round cake pans
- Parchment paper
- Hand mixer
- Wire rack
- Offset spatula
Ingredients
Main Ingredients
- 3 very ripe bananas mashed, about 1 1/2 cups
- 2 cup all purpose flour spooned and leveled
- 1 ½ cup natural unsweetened cocoa powder 3/4 cup for the cake and 3/4 cup for the frosting
- 2 tsp baking soda
- 1 tsp baking powder
- ½ tsp salt plus a pinch for the frosting
- 2 large eggs
- 1 cup buttermilk or 1 tablespoon vinegar stirred into 1 cup milk
- ½ cup vegetable oil
- 3 tsp vanilla extract 1 teaspoon for the cake and 2 teaspoons for the frosting
- 1 ½ cup granulated sugar
- 1 cup unsalted butter softened, for the frosting
- 3 ½ cup powdered sugar
- ½ cup heavy cream add a splash more if the frosting is stiff
Instructions
Cooking
- Prep. Heat the oven to 350 degrees F and line two greased 9 inch pans with parchment.
- Mix the batter. Whisk the flour, 3/4 cup cocoa, baking soda, baking powder, and salt, then beat the eggs, sugar, buttermilk, oil, and 1 teaspoon vanilla, stir in the bananas, and mix in the dry ingredients.
- Bake. Divide between the pans and bake for 30 to 35 minutes until a toothpick comes out clean or with a few moist crumbs.
- Cool. Cool in the pans for 10 minutes, then on a rack for about 1 hour.
- Frost. Beat the butter, powdered sugar, remaining cocoa, cream, 2 teaspoons vanilla, and a pinch of salt until creamy, then stack and frost the layers.
- Rest. Let the cake sit for 30 minutes before slicing and add banana slices just before serving.
