Peanut butter buttercream is mixed with lots of toasted coconut and chopped dry-roasted salty peanuts. A layer of white chocolate ganache in the center of the cake fully completes the flavors of the Zagnut candy bar.
Make the cake: Preheat the oven to 350°F. Coat a 13×9-inch baking pan with flour-based baking spray (recommend Baker’s Joy).
In a large mixing bowl, whisk together the flour, baking powder, soda and salt.
In the bowl of an electric mixer, whisk together the eggs, sugar, vanilla and vegetable oil. Add the dry ingredients to the bowl, alternating with the buttermilk while mixing on low speed. Mix until a smooth batter is formed.
Pour the batter into the pan and spread evenly. Bake for 30 minutes, or until a toothpick tester comes out clean. Cool completely on a wire rack. When the cake is cool, level the top gently using a cake leveler or serrated knife. Use the cake leveler again to torte the cake down the center.
Make the ganache: Place the white chocolate and heavy cream in a microwave-safe bowl. Heat for 1 minute, or until the cream is hot and not boiling. Let stand for 1 minute, then whisk together until smooth. Refrigerate until the mixture is of spreading consistency, about 40 minutes.
Make the Zagnut filling: In the bowl of an electric mixer, combine the butter and peanut butter. Whip until light and fluffy. Add the powdered sugar and beat again until incorporated. Stir in the coconut, peanuts, extract and pinch of salt. Beat until the dry ingredients are dispersed throughout the buttercream.
Make the buttercream: In a stand mixer fitted with the whisk attachment, mix the butter and confectioners’ sugar by starting the mixer on low speed. Continue on low speed and beat ingredients together until the mixture is crumbly. Increase speed to high and beat for 3 minutes. Add vanilla extract and beat together again for another minute until light and fluffy. If the buttercream is too stiff, add milk or heavy cream a tablespoon at a time until the mixture is of spreading consistency.
Assemble the cake: Place the bottom half of the sheet cake on a serving plate or cake board. Spread the white chocolate ganache onto the cake, followed by the Zagnut buttercream. Top with the second half of the sheet cake. Frost the entire cake evenly with the white buttercream. Place leftover frosting in a piping bag fitted with a large French pastry tube and pipe shell borders around the top and bottom edges of the cake. Add other decors and sprinkles, if desired.
Keyword american buttercream, champagne ganache, creamy peanut butter, white chocolate ganache, zagnut