Preheat oven to 400 degrees.
Beat 1 1/2 cups sugar, butter, shortening, and eggs in a large bowl with a stand mixer (using paddle attachment) or a hand mixer on medium speed.
In a medium bowl, whisk together flour, cream of tartar, baking soda, and salt. Stir or mix dry ingredients into wet ingredients.
Shape dough into balls approximately 1 1/4 inches in diameter. In a small bowl, combine the cinnamon-sugar mixture. Roll balls in cinnamon-sugar mixture and place two inches apart on ungreased cookie sheet (may use parchment paper if desired).
Bake 8-10 minutes (we found 8 minutes to be the sweet spot in our oven), or until set. Note: cookies will appear under-done, but will firm up as they cool.
Wait two minutes, then remove to a wire rack to cool.
Recipe slightly adapted from Betty Crocker's Bridal Edition Cookbook.