Cream together butter, shortening, sugar, eggs, and vanilla. Mix in flour, cream of tartar, soda, and salt. Roll rounded spoonfuls into balls.
Cinnamon Sugar
3 Combine remaining sugar and cinnamon in a small bowl. Roll balls of dough in mixture.
4 Place dough on prepared cookie sheet and bake 8-10 minutes or until set but not firm. Remove immediately from baking sheets to cool on wire rack.