For this we’re just trying to get the cake layers, not the frosting. You can use vanilla cake layers if you don’t want to have chocolate cake layers when you're baking something.
3/4 pound softened unsalted butter
3 cups sugar
9 large eggs, separated
1 1/2 teaspoon vanilla extract
3 cups cake flour
1 1/2 teaspoon baking powder
3/4 teaspoon baking soda
3/4 teaspoon salt
1 1/2 cup buttermilk
1. Preheat the oven to 350 degrees F. Butter two deep (approximately 4 inches) 9-inch cake pans and set them aside.
2. In a bowl, with an electric mixer, cream the butter, add the sugar a little at a time, and beat the mixture until it is light and fluffy. Beat in the egg yolks, one at a time, and the vanilla. Reserve the egg whites.
3. Into a bowl sift the cake flour, baking powder, baking soda, and salt.
4. In a bowl with an electric mixer beat the whites until they just hold their shape. Add the dry ingredients and buttermilk alternately into the butter mixture. Do not overbeat. Fold in the egg whites.
5. Divide batter between the pans, filling them about 2/3 full. Bake for 35 to 40 minutes, or until a cake tester inserted in the centers comes out clean. Let cakes cool in the pans for 5 minutes and invert onto racks to cool completely.
6. Fill, frost, and decorate the cake with the frosting.
Credit to some website I found the recipe on. I don't remember what it was and I hit x too fast to check.