Makes enough to cover one 8-inch / 20cm triple-layer cake or two 9 by 13-inch / 23 by 33cm sheet cakes. For the cake pictured here and in my YouTube cake tutorials, you’ll use half for the filling with raspberry preserves and half will be kept vanilla for the outside of the cake. Divide the finished buttercream into two bowls and add 1/4 cup raspberry (or other flavor) preserves to one of the bowls.