Marshmallow fondant is a great alternative for cake decorating.
It is fun to use and easy to make. Not to mention that it is extremely yummy!
This is not so much of a recipe as it is a method. No measuring required.
Photo from Clockwork Lemon
marshmallows (large or small)
Place a few handfuls of marshmallows in a microwave safe bowl (3-4 handfuls of small marshmallows frosted a double layer 9" cake).
Microwave in 10-30 second intervals until they are easy to stir.
Separate marshmallows into different bowls if you are going to be making different colors.
To each bowl, add food coloring - You want to make it darker than the color you want it to turn out like, since you will be adding powdered sugar.
Pour marshmallow mix into a mixer bowl and attach the kneading blade.
Add powdered sugar to the bowl and knead until fondant is no longer sticking to blade and bowl.
Transfer to counter onto wax paper.
Add more powdered sugar and knead until fondant is no longer sticking to your fingers and hands, and is stiff enough to roll out.
Can be stored in an airtight container for months until ready to use (do not refrigerate).
To frost cake:
Put a thin layer of icing on cake to help fondant adhere to it.
Roll out fondant and layer over icing.
Smooth out with fingers.