Melt marshmallows and 2 tbs. of water in microwave or double boiler. (Microwave in 30 second increments, stirring in between until the marshmallow is melted. Usually a total of 1 minute.).
Mix ¾ of the powder sugar with the melted marshmallow.
Grease your hands with Crisco and knead the mixture, gradually adding the remaining sugar for at least 8 minutes.
You can add food coloring at this point. Working it in the mixture.
You may refrigerate, double wrapped in plastic for weeks if you want, when ready to use just reheat in microwave for about 10-20 seconds. DO NOT FREEZE Fondant.
Your cake must be completely cooled, add a thick coating of icing to the cake. (gives a smooth finsh and helps fondand to adhere to the cake. Figure what size you need to cover your cake. (9 inch cake with 3 inch sides 3+9+3=15 plus 1 for extra so you need a 16 inch circle cut.).
Do not store cake in refrigerator once the fondant is placed on cake. Moisture will destroy the surface. Store in a sealed container.