Salt Lake City- Michele Foster's Fondant recipe calls for cream- no marshmallows. It is used by many here on Cc and is very good from what I hear and i am excited to try it.
here is the link to the recipe:
The question of the OP was referring to MFF (Michele Foster's Fondant), not MMF (marshmallow fondant). All these acronyms get so confusing.
I use half and half, cause I already keep it stocked for my coffee, heavy cream is absolutely not necessary.