- Preheat oven to 375°. Cream butter and 1 cup sugar until light and fluffy; beat in egg and vanilla. In another bowl, whisk together flour, baking soda and cream of tartar; gradually beat into creamed mixture.
- In a small bowl, mix cinnamon and remaining sugar. Shape dough into 1-in. balls; roll in cinnamon sugar. Place 2 in. apart on ungreased baking sheets.
- Bake until light brown, 10-12 minutes. Remove from pans to wire racks to cool.