In a large bowl, using an electric mixer or stand mixer cream together butter, ½ cup brown sugar and ¼ cup white sugar until well mixed.
½ Cup (113 ½ g) Butter, ½ Cup (110 g) Brown Sugar, ¼ Cup (50 g) Sugar
Add in pumpkin and vanilla, continue mixing until well blended.
⅓ Cup (81 ⅔ g) Pumpkin Puree, 1 Teaspoon Vanilla
In a separate bowl whisk together flour, 1 ½ teaspoon pumpkin spice, cream of tartar, baking soda and salt.
1 ½ Cup (187 ½ g) Flour, All Purpose, 1 ½ Teaspoon Pumpkin Spice, 1 Teaspoon Cream of Tartar, ½ Teaspoons Baking Soda, ¼ Teaspoons Salt
Add the flour mixture to the pumpkin mixture gradually, mixing between each addition until all the flour has been incorporated.
Cover the bowl and refrigerate for at least 4 hours.
When ready to bake-
Preheat the oven to 350 and line your cookie sheet with parchment paper.
Stir together the ¼ cup sugar and 2 teaspoon pumpkin spice in a small bowl or shallow dish
¼ Cup (50 g) Sugar, 2 Teaspoons Pumpkin Spice
Scoop dough out 1 tablespoon at a time and roll into a ball. Place ball in the sugar and pumpkin spice mixture and roll around to cover. Place on your prepared baking sheet.
Continue rolling the dough into balls and coating with the sugar mixture, placing them about 2 inches apart on your baking sheet.
Bake for 11-13 minutes or until the top begins to crack.
Allow to cool on the baking sheet for 5 minutes and then move to a wire cooling rack to cool completely.