sudden saturday sugar cookies

I wished I had halloween sprinkles and black piping icing when I randomly decided to make these on a saturday afternoon.

I made these partially because I thought it would be fun to decorate halloween cookies, but mostly because I had three egg yolks in the fridge, crying out not to be wasted. And this recipe fit the bill!

{"melt in your mouth" sugar cookies}
via Better Homes and Gardens' The New Cookbook
{ingredients}
1/2 c. butter, softened
1/2 c. shortening
2 c. sugar
1 teaspoon baking soda
1 teaspoon  cream of tartar
1/8 teaspoon salt
3 egg yolks
1/2 teaspoon vanilla
1 3/4 c. all-purpose flour
{directions}
In a large mixing bowl beat butter and shortening with an electric mixer on medium high for about 30 seconds. Add sugar, baking soda, cream of tartar and salt. Beat until combined, scraping sides of bowl occasionally. Beat in egg yolks and vanilla until combined. Beat in as much flour as you can. Stir in remaining flour.

Shape dough into 1 inch balls. Place 2 inches apart on an ungreased cookie sheet. Bake in a 300 degree oven about 15 minutes or until sides are set but not brown. Cool on cookie sheet for 1 minute. Transfer to wire rack and let cool.