is there any concern with the thickness of buttercream under the mmf layer? i have seen postings about bc going 'spongey' and don't want to bubble the mmf....do i have to omit bc on the top layer (other than crumbcoat) to keep mmf (or any fondant) flat, or am i safe with some bc underneath? also, any 'typical rule' for cake layer to bc layer thickness ratio? thanks very much.
Bump! I use a crumb coat of BC under my mmf but I have had bubbles from a thicker layer of BC