Cassia - from Torrance, CA
We don't recommend placing fondant cakes in the refrigerator because the moisture inside the 'frig, as well as any condensation that may form when the cake is removed from the refrigerator, can ruin the finish and look of the fondant. Since your filling needs to be refrigerated, though, the cake should be refrigerated.
Ideally, place the cake in a box, then overwrap with freezer or plastic wrap or aluminum foil. You could also wrap the cake alone in plastic wrap or aluminum foil. When removing the cake from the refrigerator, keep the cake in its wrapping until it comes to room temperature – then any condensation that develops will be on the wrapping not the cake!