Instructions

1. Cream together butter, shortening, and white sugar.
2. Beat in eggs, then stir in vanilla.
3. In a separate bowl, whisk together flour, cream of tartar, baking soda, and salt.
4. Gradually mix dry ingredients into wet ingredients.
5. Roll dough into balls, then coat in a cinnamon-sugar mixture.
6. Place on baking sheets and bake at 400°F for 8-10 minutes.