This fluffy, moist, and RICH chocolate sheet cake piled high with fudgey chocolate buttercream is beyond easy to make but it will become a favorite!
My easy chocolate sheet cake is basically perfect. So fluffy and FULL of chocolate flavor, without being oily and sad like so many store bought cakes. A nice dollop of fudge transforms this buttercream into something almost magical but if you don’t have any handy try adding in some ganache!
For the Buttercream: You can either make a simple ganache by melting chocolate and cream, or you can use a nice runny fudge. In the recipe video I used fudge but have heard from many of you that finding the right type of fudge can be a bit tricky so if in doubt just make a ganache!
Buttermilk: I love using buttermilk in cakes but it’s not something you always have on hand so feel free to either use some buttermilk powder OR sour some milk with lemon juice or white vinegar. About a tablespoon or either mixed into a cup or milk will do the trick.
Ingredients
For the Cake
▢1/2 cup sour cream 115g
▢1 cup buttermilk 236mL
▢3 large eggs
▢1 1/2 cup coffee 354mL, strong and hot
▢3/4 cup vegetable oil 177mL
▢1 tablespoon vanilla extract 15mL
▢3 cup all-purpose flour 360g
▢2 2/3 cup granulated sugar 530g
▢1/2 cup cocoa powder 50g
▢1 1/2 teaspoon baking powder 6g
▢1 tablespoon baking soda 18g
▢3/4 teaspoon kosher salt 4g
For the Frosting:
▢1 1/2 cups unsalted butter 330g
▢½ cup cocoa powder 50g
▢3/4 teaspoon salt 4g
▢1 pound confectioners sugar 453g, sifted
▢⅓ cup fudge 100g OR ganache
Instructions
For the Cake:
Preheat to 350 degrees. Line a 9×13 inch cake pan with parchment.
Sift together the flour, sugar, salt, baking soda, baking powder and cocoa powder into a large bowl and whisk to combine.
Add the sour cream, buttermilk, eggs, vanilla, and vegetable oil into a medium bowl and whisk together then pour in the coffee and mix once more.
Add the wet ingredients to the dry ingredient bowl.
Whisk to combine then mix on low for about a minute.
Pour batter into the lined pan. Bake for about 50 minutes or until a toothpick inserted in the center comes out clean.
Allow to cool for a few minutes then invert onto wire rack. Peel parchment paper off and let cool fully.
For the Frosting:
If you’re using a nice runny fudge then have that ready. If you don’t have that on hand then melt about 1/4 cup milk or cream with 1/4 cup dark chocolate, mix to combine then set aside to cool. Cream butter in a stand mixer fitted with a paddle attachment. Beat in cocoa powder and salt and mix until combined.
Add the confectioners sugar in a few batches mixing in on low. Scrape the bowl down and mix once more.
Add fudge or ganache in and mix until well combined. You can add milk or cream in a tablespoon at a time to thin the consistency out If needed.
For the Assembly:
Add buttercream to the top of the cake with an ice cream scooper. Spread over with an offset spatula.
Decorate with sprinkles, chopped toasted nuts or shaved chocolate