To assemble the cake:
3. Frost the cake. Place 1 layer, rounded-side down, in the middle of a rotating cake stand. Using a palette knife or offset spatula spread some of the ermine frosting over the top of the cake. (Spread enough frosting to make a 1/4 to 1/2-inch layer.) Carefully set another layer on top, rounded-side down, and repeat. Top with the remaining layer and cover the entire cake with the remaining frosting.