You are looking for a recipe for rolled fondant The recipe I have is for a white chocolate rolled fondant. It is:

14 ounces melted white chocolate or vanilla chips melted in a double boiler.
Add 1/3 cup Karo syrup and stir in.

It will look like the oil is separating from the mix, but cover it with saran wrap and let sit 24 hours. It will be hard, but knead until soft. I don't have a recipe for the other type rolled fondant.

The recipe above is a lot of work, but it is worth it because you will have a cake frosting that tastes good, whereas the rolled fondant you buy is tasteless to me.