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The Most Delicious Banana Split Sheet Cake

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Banana cake layers in a sheet pan, banana & strawberry buttercream, chocolate ganache drizzle, sprinkles, and cherries on top!
Servings 24 square slices
Author Mandy Merriman - Baking with Blondie

Equipment

  • 1 Wilton 1M piping tip
  • 1 squeeze/ganache bottle
  • 1 scalloped decorative cake comb/scraper

Ingredients

Banana Cake

  • 4 egg whites room temperature
  • 3/4 cup buttermilk
  • 2/3 cup sour cream
  • 1 Tablespoon vanilla
  • 1 teaspoon banana extract *optional
  • 1/3 cup vegetable oil
  • 1 cup ripe mashed bananas (about 2 bananas)
  • 1 15.25oz White Cake Mix (Duncan Hines)

Small Batch Banana Buttercream

  • 2 sticks (or 1 cup) unsalted butter
  • 1 pinch salt
  • 2 teaspoons vanilla
  • 1/2 teaspoon banana extract
  • 1/8 cup heavy cream
  • 4-5 cups powdered sugar
  • 1 drop yellow gel coloring

Small Batch Strawberry Buttercream

  • 2 sticks (or 1 cup) unsalted butter
  • 1 pinch salt
  • 2 teaspoons vanilla
  • 1 teaspoons strawberry emulsion
  • 1/2 cup freeze dried strawberry powder (1/2 cup AFTER the food processor)
  • 1/4 cup heavy cream
  • 4-5 cups powdered sugar

Ganache Drizzle

  • 1 cup chocolate candy melts
  • 1/2 cup heavy cream

Extras

  • 1 cup rainbow sprinkles
  • 1 cup stem-on maraschino cherries

Instructions

For the Banana Sheet Cake

  • Preheat the oven to 325 degrees convection bake, then prep a 9x13 pan with a swipe of shortening and dust of flour. Set aside.
  • In a large bowl, hand-whisk together all the ingredients for the cake except for the cake mix. Sift in the cake mix, gently stir until it's combined, then pour the batter into the prepared cake pan. Bake for 25-27 minutes. Cool on a cooling rack in the pan or flip out onto the cooling rack if you're frosting the sides of the cake.

For the Banana Buttercream

  • With the paddle on a stand mixer, whip up the butter until it's light and fluffy, then add in the salt, vanilla, banana extract, and heavy cream and mix again.
  • Add in the powdered sugar, then whip up again on high speed for 2 minutes until it's light and fluffy. Add in more heavy cream (1 Tablespoon) if needed. Add in the gel coloring to make it yellow.
    Use a wooden spoon to hand-beat out the air bubbles to make a smooth and silky buttercream.

For the Strawberry Buttercream

  • With the paddle on a stand mixer, whip up the butter until it's light and fluffy, then add in the salt, vanilla, strawberry extract, strawberry powder, and heavy cream and mix again.
  • Add in the powdered sugar, then whip up again on high speed for 2 minutes until it's light and fluffy. Add in more heavy cream (1 Tablespoon) if needed.
    Use a wooden spoon to hand-beat out the air bubbles to make a smooth and silky buttercream.
    Add the buttercream to a piping bag fitted with a 1M piping tip.

For the ganache

  • Add the chocolate and heavy cream together in a microwave safe bowl. Heat in the microwave for 30 seconds and stir. Heat for 10 minutes and stir again. Repeat until the chocolate is smooth and melty. Add to a squeeze bottle for the chocolate drizzle.

Assembly

  • With an offset icing spatula, spread out the banana buttercream in a flat layer on the cooled sheet cake. Use a scalloped cake scraper to make the pattern on the buttercream surface.
    Drizzle on the chocolate ganache across the cake then add on the sprinkles around the outside rim of the cake.
  • Swirl on strawberry buttercream on the outside edges, and place on a maraschino cherry. Enjoy!

Notes

Recipe source: Cake Confidence, Mandy Merriman (me)