In a large bowl, beat 1 egg with 1 cup softened butter or margarine until light and fluffy. At low speed of an electric mixer, add 1/2 cup sour cream, 1 teaspoon vanilla and dry ingredients. Mix until combined using hands if necessary. Cover dough and refrigerate for several hours or overnight.

Remove dough from the refrigerator. Preheat oven to 375 degrees. Roll chilled dough out on a lightly floured surface to 1/8 inch thick. Cut dough into desired shapes. Place on ungreased cookie sheets and bake at 375 for 10-12 minutes.