In a large bowl whisk together flour, baking soda, cream of tartar, salt and pumpkin spice. Seat aside.
In a large bowl, cream together butter , shortening, granulated sugar and brown sugar.
Mix in eggs, vanilla extract and pure pumpkin puree.
Gradually add the dry ingredients into the wet ingredients until a dough has form.
Cover bowl with plastic wrap and refrigerate overnight (this will firm up the dough)
Preheat oven to 325 F. Line a baking sheet with parchment paper & set aside.
Mix together the sugar coating ingredients and set aside.
Scoop out a heaping tablespoon of chilled dough, roll into a ball and coat in the sugar mixture.
Place on the prepared baking sheet 2-inches apart. (refrigerate remaining dough between batches)
Bake for 11-12 minutes.
Remove from oven and let cookies sit on the pan for 2 minutes before moving to a cooling rack to finish cooling.
Store cooled cookies in an air-tight container.