Tips: When the cake has cooled it takes me about 30 minutes to make the frosting and frost the cake. A more casual frosting job will take less time. To smooth the frosting on easily plan to frost the cake as soon as you make the frosting. Also try smearing just a little down all around the sides and top of the cake to make what is called a “glue layer.” Don’t worry about getting crumbs in it. Put your clean frosting over the glue layer for easy but polished look.