Pound cake has a natural dense consistency due to the large amount of whole eggs, butter and flour used. Original pound cake recipes called for one pound each of flour, butter, eggs and sugar – thus the name. Today, pound cake mixes are moister and less dense, due to added emulsifiers that perform functions such as strengthening protein and adding aeration to the cake. However, they still work well under the weight of fondant.

Traditional white and chocolate cake mixes are too tender to support fondant when baked as per box instructions. However, by adding ingredients such as instant vanilla pudding mix and sour cream to the batter, the cake can be made firmer and denser to support the fondant covering. Other methods include the addition of flour, sour cream and sugar, and increasing the amount of whole eggs called for in a traditional 18-ounce box of cake mix. Flavorings should also be adapted to compensate the extra ingredients, with the addition of vanilla extract for white cakes, or cocoa powder for chocolate cakes.

Carrot cake is a firm yet moist cake with a dense structure supplied by grated carrots and whole eggs. It is dense enough to support fondant; however, the addition of coconut, pineapple, raisins and nuts to a boxed mix will add extra weight and structure.

Using a buttercream frosting between the fondant and cake will allow the fondant to stick better to the cake. It will also act as an opaque barrier between dark cake and light fondant. Fondant-covered cakes require a firm filling to add structure. Buttercream and ganache work best with fondant cakes. However, if using a cream cheese frosting for filling, add buttercream frosting to the outside edges, as cream cheese can soften and cause movement between layers. Fondant does not stick well to cream cheese frosting. Do not refrigerate a fondant-covered cake as moisture beads may occur and fondant will become sticky. Instead, store it in a cool, dry place.