I've been told that it's easier to carve frozen cakes. I've baked a 3D cake, and frozen it, and am now carving it into the desired final shape. Once that's done, should I allow it to thaw before frosting with buttercream, or do it while it's still cold? I plan to cover it with fondant, after frosting, and I want to be sure that I don't do something that's going to adversely affect the way the final product looks! Thanks!