Preheat the oven to 350°F. Line two baking sheets with parchment paper and set aside.

In a large bowl, cream together the butter, shortening, granulated sugar, and eggs until combined and creamy.

Sift together the flour, cream of tartar, baking soda, and salt. Gradually add to the wet ingredients, mixing until the dough comes together.

In a small bowl, combine the 2 tablespoons of cinnamon and 2 tablespoons of sugar, stirring until well mixed.

Using a cookie scoop, scoop dough and form it into round balls. Roll each ball in the cinnamon-sugar mixture until fully coated.

Place the coated dough balls on the prepared baking sheets, spacing them about 2 inches apart.

Bake for 8-10 minutes until the edges are lightly golden. Allow the Snickerdoodles to cool for 2-3 minutes on the baking sheet before transferring to a wire rack to cool completely.