The whole point of covering a cake in fondant is to give it a perfectly a very thin coat of frosting under a thicker outer layer of buttercream.
The icing on your cake (under the fondant) should be as smooth and icing spatula to get my buttercream smooth before I apply my fondant.
Use this recipe for buttercream that goes under fondant. Half the recipe See More. Crusting Cream Cheese Buttercream Frosting Recipe #icing See More. Pro Tip: How to Cover a Round Cake with Fondant #cakedecorating (scheduled via.