Fondant is an edible coating that adds a smooth, glossy appearance to cakes. It has a sugar base and is heated until it forms a pliable sheet. Fondant is often an integral part of the cake-decorating process, but it can be difficult to handle because it requires precise temperatures to keep its appearance once it's applied. Fondant cake may lose its shape if the storage temperature is too warm. You can freeze fondant cake if you can't use it immediately, but you must store it correctly or it will absorb too much moisture and become runny.
Wait for your fondant-covered cake to completely cool down to room temperature. Wrap the entire cake securely with plastic wrap and press down on it so that no air is trapped between the cake and the plastic.
Cover the cake tightly with another layer of plastic wrap. Repeat the wrapping process with the plastic at least one more time in order to thoroughly safeguard the fondant against any condensation from the freezer.
Wrap a layer of aluminum foil securely around the plastic layers to help prevent any tastes or scents from the freezer or storage container from transferring into the cake. Place the wrapped cake into a cardboard cake box and close tightly.
Place the cardboard cake box into the back of the freezer to ensure it stays completely frozen. Keep the cake in the freezer for no more than two months before defrosting.
Remove the cake box from the freezer and let it completely defrost in all its wrappings at room temperature. Peel off the aluminum foil and plastic wrap carefully so the condensation doesn't drip onto the cake, then serve.