1/2 cup butter, softened
1 cup plus 2 tablespoons sugar, divided
1 large egg, room temperature
1/2 teaspoon vanilla extract
1-1/2 cups all-purpose flour
1/4 teaspoon baking soda
1/4 teaspoon cream of tartar
1 teaspoon ground cinnamon
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.