Does it only happen to cakes covered in fondant? If so, try using ganache instead of buttercream. There is a thread floating around that has several youtube video links about how to make chocolate and white chocolate ganache and cover a cake with fondant using this form of icing. I only use white chocolate ganache under fondant (doesn't change the flavors any more than using buttercream). Works great in my opinion.
5/26/11 at 10:52am