Preheat your oven to 400°F.
In the bowl of a stand mixer, combine the butter, shortening, granulated sugar, and light brown sugar. Cream them together until the mixture becomes light and fluffy, which should take about 3-5 minutes.
In a separate bowl, sift together the cream of tartar, baking soda, and flour. Then, add in the eggs one at a time, followed by the vanilla extract. Mix until just combined.
Slowly incorporate the sifted dry ingredients and salt into the wet mixture until everything is just combined.
In a medium-sized bowl, mix together the pumpkin spice, cinnamon, and granulated sugar.
Line a baking sheet with parchment paper. Scoop out cookie dough balls (about 2 tbsp of dough per cookie), roll them in the cinnamon sugar mixture, and place them on the cookie sheet about 2 inches apart.
Bake for 8 minutes or until the edges are just set. Be careful not to overbake! Once done, remove from the oven and let the cookies rest on the sheet for 3 minutes before transferring them to a cooling rack.