So I want to make a cake with a white crusting buttercream, first time doing that. What cake would be good inside? The cake I usually make is best with a chocolate buttercream, which I usually cover with fondant. so do you have any ideas?

I was wondering if it's possible to cover my cake with chocolate buttercream, let it set, and then put a thick layer of white bc? does that make sense, will it work? or should i just make a different cake...

You can certainly double frost (although it sounds like a LOT of work IMHO).

This thread has the expanded flavors WASC cake and popular CC crusting b/c frosting recipes:

http://www.cakecentral.com/cake-decorating-ftopict-605188-.html

HTH