This icing goes great with my sugar cookie recipe, which you can find here: http://trinitywolf3.blogspot.com/2012/09/sugar-cookies-icing.html
1/4 c. butter, softened
1/4 tsp. vanilla
4 Tbsp. milk
lots and lots of powdered sugar
food coloring, optional
Mix the butter, vanilla, and 2 tablespoons of milk together. Add 1/2 a cup powdered sugar. Mix together. Add more powdered sugar, a quarter cup at a time until you reach the thickness you want. If your frosting gets too thick, add another tablespoon of milk, but no more than 4 tablespoons total. Continue to balance sugar and milk until you're happy with the consistency. Frost cookies however you want.
I used the frosting to make these pretty rosette cookies. They were so delicious.