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Easy Banana Snack Cake with Dark Chocolate Buttercream

This easy banana snack cake is all that you will need to satisfy your sweet tooth! A moist banana cake topped with dark chocolate buttercream is the perfect afternoon treat! You'll definitely want to keep this banana cake recipe on hand for any occasion.
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Prep Time 20 minutes
Cook Time 25 minutes
Frosting and cooling time 1 hour
Total Time 1 hour 45 minutes
Servings: 12 slices
Course: Dessert
Cuisine: American
Ingredients Method Notes

Ingredients
  

For the Banana Snack Cake
  • 1½ cups all-purpose flour
  • 1 tsp baking soda
  • ½ tsp baking powder
  • ¾ tsp salt
  • ½ tsp cinnamon
  • ½ cup light brown sugar (packed)
  • 3 medium, very ripe bananas (mashed)
  • ½ cup vegetable or canola oil
  • ½ cup full-fat sour cream (room temperature)
  • 2 tsp vanilla extract
  • 2 large eggs (room temperature)
For the Dark Chocolate Buttercream
  • ½ cup roughly chopped dark chocolate
  • ¾ cup unsalted butter (room temperature)
  • ½ tsp vanilla extract
  • 1 cup + 2 tbsp powdered sugar
  • pinch of salt

Method
 

For the Banana Snack Cake
  1. Preheat oven to 350°F. Line a 9x9 inch square baking pan with parchment paper, leaving the edges hanging off of the side (to lift the cake out when it is done).
  2. In a medium bowl, whisk together the flour, baking soda, baking powder, salt, cinnamon, and brown sugar. Set aside.
  3. In a separate bowl, combine bananas, oil, sour cream, and vanilla. Stir in the eggs until everything is well combined.
  4. Add the flour mixture to the banana mixture and stir until just barely combined (do not overmix). Pour the batter into the prepared baking pan and bake for 25-30 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs.
  5. Cool on a wire rack completely before frosting.
For the Dark Chocolate Buttercream
  1. In a medium saucepan over low heat, melt the chopped chocolate until smooth. Once melted, remove from the heat to cool slightly.
  2. In the bowl of a stand mixer fitted with the paddle attachment, or in a large bowl with a hand mixer, beat the butter on high speed until light and fluffy (about 3 minutes).
  3. Add the vanilla extract and salt and beat on medium speed until incorporated.
  4. Reduce the mixer to low speed and slowly add in the powdered sugar. Beat on low for 30 seconds and then increase the speed to medium-high and beat until smooth (about 3 minutes).
  5. Stop the mixer and add the melted chocolate to the bowl. Mix on low speed until combined. Frost cooled cake with buttercream.

Notes

  • Cake can be stored in an airtight container for up to 3 days at room temperature. 
  • Cake can be frozen and frosted later. Simply wrap in plastic wrap and foil and freeze for up to 1 month. Set cake out at room temperature before frosting.
 
High Altitude Directions:
  • Flour – increase by 2 tbsp.
  • Brown Sugar – decrease by 1/2 tbsp.
  • Baking Soda – decrease to 1/2 tsp. 
  • Baking Powder - decrease to 1/4 tsp. 
  • Eggs – use 3 eggs instead of 2. 
  • Increase oven temperature to 365° F. 
  • Decrease baking time by 5 or more minutes
 
Helpful Tools
Mixing Bowls | Pam for Baking | Rodelle Vanilla Extract | 9x9 inch baking pan