In a large bowl, using a hand mixer or a stand mixer, cream the sugar and butter. Add in shortening, eggs, and vanilla and mix until smooth and creamy. Set aside.
In a medium bowl, whisk the flour, cream of tartar, baking soda, and salt. Gradually add the dry mixture into the wet mixture, while mixing, until just combined. Chill in the fridge for 1 hour.
In a small bowl, mix the light brown sugar and pumpkin pie spice together. Scoop a heaping tablespoon amount of cookie dough and roll into a ball with your hand. Place the ball of dough into the brown sugar mixture and roll around until completely coated.
Place the cookie balls 2 inches apart on an ungreased cookie sheet. Bake for 8-10 minutes, until the cookie no longer looks wet. Remove from the oven and transfer the cookies to a wire rack to cool.