Christmas Cookies: My Grandmother's Sugar Cookies

I've eaten these sugar cookies every year for Christmas (and many Valentine's as well).  They are exactly what a cookie s hould be.  Sweet, with yummy icing that drips off the side before it dries, holding, whatever sprinkles you decide to sprinkle hostage until they make their way down to your belly.  We always dye the dough green or red, which is more like pink.  When I was little, despite the amount of color I added, they are always pink.  I love that.  I also tend to eat more dough than actual cookies, so we always double the recipe. 

Here's the recipe for My Grandmother's Sugar Cookies

Cookie Recipe: 
Mix 1/4 c. (softened) butter, 1/4 c. shortening, 3/4 c. sugar, 1 egg. 
Stir in 1 T. milk, 1 t. vanilla. 
Sift in 1 1/4 c. flour, 1/4 t. baking powder, 1/4 t. salt. 
Color and chill in syran wrap. 
Place on greased cookie sheet.  Bake at 425 degrees for 5-7 minutes. 
Icing Recipe:
Melt 1 stick butter.  add 1 box powdered sugar, 6 T. evaporated milk, 1 t. vanilla.  Bring to a slow boil, and beat if lumpy.  Let cool slightly.  Spoon over cookies, and add sprinkles and decorations.