In a medium mixing bowl, whisk together the flour, pumpkin pie spice, baking soda, cinnamon, cream of tartar, and salt. Set aside.
In a large mixing bowl, cream the butter, sugar, and brown sugar until light and fluffy.
Add the egg yolk, vanilla, and pumpkin puree to the creamed mixture. Mix until well combined.
Gently fold the dry ingredients into the wet mixture until just incorporated.
Chill the dough in the refrigerator for 30 minutes.
While the dough chills, preheat your oven to 350°F.
Once chilled, use a medium cookie scoop to portion the dough. Combine the additional sugar and cinnamon on a plate, and roll each dough ball in the mixture to coat.
Place the coated dough balls on a baking sheet, spacing them evenly.
Bake for 10-11 minutes, or until the cookies are just set.
Let the cookies cool on the baking sheet for 5 minutes before transferring them to a cooling rack to cool completely.