Add all of the ingredients, except the food coloring, in a bowl and whisk until smooth.
Add in drops of food coloring, or use a wooden popsicle stick to add drops of gel food coloring to the icing. Do not mix it. It will give it's own marbling effect when it's poured.
Place the fondant cake on a cooling rack with a cookie sheet underneath.
Pour the icing over the top and let it dry.
Notes
Nutritional values are based on the whole recipe.Use any colors of food coloring you like.