K.M.
Wrap the cake in saran wrap and put in the freezer. If you frost the cake right when you take it out, it will perspire on top of the frosting. So I would suggest waiting a little bit for it to defrost before frosting. I have make the mistake of decorating the cake and then freezing it. When it thaws in perspires and the colors on the cake run. My mom used to have a cake decorating business so that is just a tip I learned from her. By the way, the cake will be extremely moist because it was frozen.