Bukkake Cookies

1 cup unsalted butter, room temp
1 1/2 cups powdered sugar
2 teaspoons vanilla extract
1 teaspoon baking powder
1 large egg
2 1/2 cups all-purpose flour
1/2 teaspoon salt

Icing:
2 cups powdered sugar
1/4 cup milk
food coloring
various decorator icing and gels