Preheat oven to 400 degrees. Line two baking sheets with parchment paper or Silat mats.
COOKIES: In a medium bowl, mix flour, cream of tartar, baking soda and salt; set aside.
In a large bowl, using an electric mixer, beat butter and shortening, until creamy. Add 1 1/2 cups sugar and continue beating until light and fluffy. Add vanilla and eggs one at a time, beat well after each addition. With mixer on low-medium speed, mix in dry ingredients, one cup at a time, until blended. Chill the dough for 30-60 minutes.
CINNAMON SUGAR: In a small bowl, mix 3 tablespoons sugar and cinnamon together; set aside.
Shape dough by rounded teaspoonfuls into balls. Roll dough balls in cinnamon sugar.
Place about 2-inches apart on prepared baking sheets. Flatten slightly with the palm of your hand.
Bake for 8 to 10 minutes (8-minutes for softer cookies, 10-minutes for crispier cookies). Immediately slide parchment paper lined with cookies onto a cooling rack. Cool cookies completely before storing in airtight containers.