I need to know how much and what kind of frosting to put under MMF. I thought the best would be to use Crusting Buttercream, but wasn't sure since it'd be crusted and the MMF might not stick...do I spray with a little water before placing the fondant? Need to decorate a cake tomorrow. Thanks so much.
You can spray the cake with a little bit of water, but fondant is usally good about sticking to buttercream on it own.
I use white chocolate ganache under fondant. I "paint" the ganache after it has hardened with water.