Here is the recipe for butter-cream frosting. So yummy! It should be enough to cover one 2-layer 9-inch cake:
6 Cups powdered sugar---please sift! You don't want little balls of powdered sugar in you frosting.
2/3 Cup butter---b/c margarine is gross.
3 teaspoons of vanilla. Preferably clear vanilla. But if you're coloring your frosting then it doesn't really matter.
1-2 tablespoons of milk. So it says. Just add enough to make it your desired consistency. I use this recipe to frost, not decorate, so I end up adding more milk so I can have thin consistency.