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A chocolate sheet cake with swirls of fudge frosting and sprinkles
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Easy Chocolate Sheet Cake

This easy chocolate sheet cake is covered with swirls of fudge frosting and sprinkles.
Prep Time30 minutes
Cook Time30 minutes
Total Time1 hour 20 minutes
Course: Dessert
Cuisine: American
Keyword: chocolate cake, fudge frosting, half sheet cake, sheet cake
Servings: 30

Ingredients

Chocolate Sheet Cake

  • 3 cups all-purpose flour
  • 1 ⅓ cup unsweetened cocoa powder Dutch processed
  • 1 ¼ teaspoon baking soda
  • 2 ½ teaspoon baking powder
  • 1 tablespoon instant espresso powder optional
  • 1 teaspoon salt
  • 3 ¼ cups granulated sugar
  • 1 cup avocado or vegetable oil
  • 4 large eggs
  • 2 teaspoon vanilla extract
  • 1 ¾ cup buttermilk
  • 2 cup hot water

Fudge Frosting

  • 1 ½ cups unsalted butter softened
  • ½ teaspoon salt
  • 5 ½ cups powdered sugar sifted
  • ½ cup unsweetened cocoa powder
  • 1 teaspoon vanilla extract
  • 2 to 4 tablespoon milk
  • 8 oz semi or bittersweet chocolate melted and cooled

Instructions

Chocolate Sheet Cake

  • Pre-heat oven to 350 degrees Fahrenheit. Grease a half sheet cake pan (18 x 13 inches or similar) and set aside
  • Whisk or sift together the flour, cocoa powder, baking powder, baking soda, and salt. Stir in the instant coffee granules.
  • In the bowl of a stand mixer fitter with the paddle attachment, mix together the sugar and oil until smooth until some of the sugar begins to dissolve, about 2 minutes.
  • With the mixer on medium, add the eggs, one at a time. Add the vanilla. Stop the mixer and scrape down the sides of the bowl.
  • Add half of the flour mixture and mix on low speed to combine. Continue mixing while streaming in the buttermilk. Mix until smooth. Add the remaining flour mixture and mix until combined.
  • Slowly stream in the hot water and mix until the batter is smooth.
  • Pour the batter into the prepared pan and bake for 30 to 35 minutes, or until a toothpick inserted into the center of the cakes comes out clean or with a few moist crumbs.

Fudge Frosting

  • Using an electric mixer, cream the butter until soft and smooth.
  • Stop the mixer and add in the salt, powdered sugar, cocoa, vanilla, and milk. Mix on low speed until incorporated then increase the speed.
  • Mix on medium until soft and silky, yet not runny, adding more milk as needed.  
  • Stop the mixer and scrape down the bowl.
  • Add in the melted chocolate and mix until combined.

To Assemble

  • Wait until the cake completely cools before adding the fudge frosting. Reserve about 2 cups of the frosting for the swirly boarder.
  • Spread the remaining frosting all over the center of the cake. Use an offset spatula to smooth it out as best as possible
  • Pipe a reverse shell boarder using a 4B star tip around the edges.
  • Decorate with sprinkles.