You frost a cake by applying a thin crumb coat of icing over the top and sides, then chilling the cake in the refrigerator for twenty minutes to lock in crumbs. After the initial layer sets, apply a generous second coat of frosting using an offset spatula for a smooth, clean surface. Smooth out the top and edges using a bench scraper while rotating the cake stand. Decorative borders or piped designs can then be added using a pastry bag.