Preheat oven to 400℉. Line baking sheet with parchment paper.
In electric mixer combine the butter, shortening, 1 ½ cups sugar and the eggs, mix thoroughly on medium speed until creamy and well combined, 1 to 2 minutes.
Sift together the flour, cream of tartar, baking soda and salt, and stir into the shortening mixture.
In a small bowl, stir together the remaining 2 tablespoons sugar with the cinnamon.
Shape the dough into 1 ½-inch balls (I use the 1 ½ inch cookie scoop), and roll each ball in the cinnamon-sugar. Arrange the dough balls 2 inches apart on cookie sheets.
Bake until the edges of the cookies are set but the centers are still soft, 8 to 10 minutes. Transfer the cookies to wire racks for cooling. Repeat with the remaining dough balls.