If you're going to make marshmallow fondant, I suggest making it the night before and letting it firm up in the fridge. A word of advice, though - you'll only want to use fondant for these if they're going to be eaten right away and if you decorate with fondant at the last second. :D
I am not the most accomplished baker, and had no idea that marshmallow fondant does not firm up over time! The cat heads got a little soft after being on top of the icing for a while, especially the thinner ones.
This is the fondant recipe I used:
8 oz mini marshmallows
2 tablespoons water
1 pound powdered sugar
crisco as needed!
I'd click through and read the tutorial - that lady knows what she's doing! :D
The basic jist of it is to put the two tablespoons of water and 8 oz of mini marshmallows in the microwave in a HUGE bowl, 30 seconds at a time. After every 30 seconds, stir them and pop them back in. Keep doing this until they're nice and smooth.
Once that's done, dump 3/4 of the powdered sugar into the marshmallows and coat a spatula with crisco and stir stir STIR.
Don't stop stirring until most of it is combined. The fondant should be forming a bit of a ball at this point. Then grease your counter AND hands with crisco, dump the lump out of the bowl and knead it like crazy. If it's still super sticky, keep putting powdered sugar on top and mixing it in. After 5-10 minutes of adding powdered sugar and kneading, you should have a smooth, barely sticky piece of fondant.
Coat it in crisco, wrap it in plastic wrap, and pop it in the fridge until you're ready to work with it.
I apologize for the lack of photos - maybe one day I'll do a tutorial over it. I just really wasn't sure how it was going to go so I didn't bother documenting it. :P