In a mixing bowl, cream butter and sugar until smooth. Scrape down bowl as needed to ensure thorough mixing. Add pumpkin puree, vanilla, and egg. Mix until combined.
In a large bowl, whisk together flour, baking powder, baking soda, cream of tartar, salt, pumpkin pie spice mix, and ground cinnamon. Add to butter mixture in three additions. Mix on low speed until there are no longer any dry streaks of flour.
Cover dough and keep chilled in the fridge for at least 2 hours until dough is firm (or up to 24 hours).
Preheat oven to 350℉. Line baking sheets with parchment paper or silicone baking mats.
In a small bowl, whisk together sugar, spice mix, and cinnamon to make sugar spice mixture. Set aside. Using a 1 ½-tablespoon cookie scoop (#40 scoop), portion out chilled cookie dough. Roll cookie balls in sugar spice mixture until fully coated. Place cookie balls 2-inches apart on prepared baking sheet.
For flatter cookies: gently press the cookie balls with the palm of your hand or the bottom of a drinking glass. Bake for 8-10 minutes until the edges of the cookies are set. Allow to rest in baking sheet for 3 minutes before transferring to wire rack to cool. Enjoy cookies warm or at room temperature.
For natural, puffier cookies: Bake cookie balls as is. Bake for 10-12 minutes until the edges of the cookies are set and the center of the cookies have puffed up. Allow to rest in baking sheet for 5 minutes before transferring to wire rack to cool. Enjoy cookies warm or at room temperature.