Hey Guys...I am looking for a good MMF recipe. The one I use is hardening up to much and it has to sit for 12 hours before use. Are all recipes like that?? 

The one I use doesn't need to sit for 12 hrs. Think it's 300g marshmallows, 3 tbsp butter, 3 tbsp water and 1 kg icing sugar plus some shortening for the hands. But am not home and would honestly need to confirm exact measurements when back if you want.  Many times I actually skip the water. And I add my food coloring to the melted marshmallows for a big batch Inn the same color. 

Mmf always gets stiff and can't be kneaded soft like rolled fondant btw. You'll have to pop it into the microwave for a few seconds in order to work with it. Maybe that's the problem and not your recipe?

@julia1812 Thanks...that's pretty close to the recipe I use. I never thought to pop it in the microwave. Thanks. Hopefully that will help! I have seen some recipes with syrup and I was wondering if that would.make any difference. 

I just made a batch last night and mine is SO elastic and soft that I am not sure if it will roll out right.   (I think it may have to do with the heat in my kitchen) This is the total opposite of what you are experiencing.   

I use this artisan cake company's recipe.   I like it because it's a little unorthodox in method. 

I use Macsmom's recipe (here on CC). The amount of powdered sugar changes based on the temperature, etc.

you have to gauge it everytime you make fondant. Otherwise, you may be left with a fondant that is too soft or too stiff. It will get stiffer as it cures...so you have to take this into consideration.

Here it is: http://www.cakecentral.com/recipe/7351/marshmallow-fondant-macsmoms-bc-flavored-variation