Whipped Shortbread

Where did this recipe come from?  My recipe box.  Before that?  who knows?

2 cup butter
1 cup icing sugar
3 cups flour
1 cup corn starch
decorations (candied cherries or sprinkles)

Using a heavy duty mixer, beat butter on medium speed until light and fluffy. Stir together dry ingredients and slowly add to the butter while beating. With shortbread there are no wet ingredients so there's no fear of over mixing. Still, beat until it's all blended. Roll dough into little balls, dip into the sprinkles or decorate with cherries and place on baking sheet.
Bake at 300F for 20 minutes or so. The cookie should be set and barely golden on the bottom.