Preheat oven to 375 degrees F. Line a baking tray with parchment paper or silpat liner.

Combine wet ingredients: Mix together butter and shortening until smooth. Add granulated sugar and brown sugar and cream together for a few minutes, until light and fluffy. Mix in egg, pumpkin, and vanilla.

Add dry ingredients: Add the flour, pumpkin pie spice, cream of tartar, baking soda, and salt and stir until combined.

Refrigerate dough for 10 minutes. Meanwhile, in a separate small bowl mix 1/4 cup granulated sugar and 1 Tablespoon ground cinnamon. Roll dough into 24 dough balls.

Roll dough balls in cinnamon sugar. Place on baking sheet, 2 inches apart. Using the palm of your hand or bottom of a glass, lightly flatten each cookie dough ball.

Bake 8 to 10 minutes (don't over bake!) Remove immediately to a cooling rack to cool completely.