The Best Chocolate Banana Cake

Soft Chocolate Banana Cake Layers with fresh bananas, and the most delicious cocoa buttercream and mini chocolate chips.

3/4 cup buttermilk room temperature
1/3 cup sour cream room temperature
3 whole large eggs room temperature
2-3 medium ripe bananas the more brown the better
1/3 cup vegetable oil
1 Tablespoon vanilla
1/2 cup mini chocolate chips optional
1 15.25oz Chocolate Cake Mix I used the Dark Chocolate Duncan Hines for the best taste and texture

1 1/2 cup (or 3 sticks) unsalted butter left out at room temperature for 10 minutes
pinch of salt
1 Tablespoon pure vanilla
1/2 + 1/2 cup heavy cream (plus 1/2 cup more after adding in the dry ingredients to thin out the buttercream
1/2 cup quality cocoa powder
7 cups powdered sugar

This recipe can be made into three 6" cake rounds, two 8" cake rounds (thick), or three 8" cake rounds (thin). The photos you see here are the three 8" cake rounds.
Prep cake rounds with a swipe of shortening and a dust of flour.
Preheat oven to 325 degrees (convection bake). If doing traditional bake, you will just need to leave the cakes in for about 2-3 minutes longer.
In a large bowl, hand-whisk together all the ingredient except for the mini chocolate chips and cake mix. When thoroughly combined, stir in the chocolate chips, then sift in the cake mix. Gently stir it in, then split between the prepared cake pans. Bake for 20-25 minutes, or until the center of the cake is baked through.
Flip cake rounds out carefully onto a wire rack to finish cooling, wrap up in plastic wrap, then store in the freezer until you're ready to assemble the cake.

In a stand mixer fitted with a paddle attachment, whip up the butter until it's light and fluffy. Scrape down the sides of the bowl.
Add in the pinch of salt, vanilla, 1/2 cup heavy cream, and cocoa powder. Mix up again to combine.
Slowly add in the powdered sugar, about 1/2 cup at a time. The buttercream will turn into an almost powder-like mixture, but don't worry! Add in your last 1/2 cup of heavy cream and it should thicken right up into buttercream.
Flip the mixture on high speed for 2 minutes, and add in a touch more heavy cream if needed to thin (your cocoa powder sometimes affects how thick or thin the buttercream will turn out for this one, I've noticed). If it's too thick, add in a touch more (2 Tablespoons-ish) of heavy cream. If it's too thin, add in 1/4 cup more of the powdered sugar. You're in charge of the consistency.

On a cake turntable, and on a cardboard cake round, add on a dot of buttercream and carefully spread it out with an offset icing spatula. Place down the first cake layer.
Add on a layer of buttercream, then the next cake layer, and repeat. Crumb coat the cake and freeze for 3 minutes.
With a wooden spoon or spatula, hand-stir the buttercream to get out any air bubbles before adding on the final layer of buttercream to the cake. This will help it smooth out the buttercream much easier.
Spread on the rest of the buttercream onto the cake, use the cake turntable and offset icing spatula to create the swirl on top, and use a cake scraper (inverted scallop for this one) to create the decorative sides, leaving the top unfinished for a more rustic look.
Add on some mini chocolate chips on top around the outside rim of the cake. Enjoy!