Originally Posted by yortma
To defrost cakes I take off the several layers of plastic wrap, and then just lay one piece loosely over the top of the cake while it defrosts. I take them out a half hour or so ahead of time, depending on the room temperature. It doesn't take very long to defrost single layers of cake, so they are not sitting out much. I also frequently start to assemble and frost before the cakes are completely defrosted. That seems to work just fine, and the cakes never sit out for long. I have not been worried about them drying out.
I only just made my first fondant cake, but based on everything I read on this site and elsewhere, that's what method I went with.. I took my cake out for about 20-30 minutes, then put on my crumb coat, put back in the fridge uncovered for another 20 minutes, took out and did the second layer of buttercream, then put the fondant on. My cake was frozen before but it had already started to thaw out a little. then after the fondant I just let it sit on the counter, seems like it worked out perfectly for me! Good luck.