Preheat the oven to 375F. Line two baking sheets with parchment paper.
For the Cinnamon Sugar:
In a small bowl, whisk together the sugar and cinnamon. Set aside.
For the Cookie Dough:
In a large bowl, whisk together flour, spices, baking soda, cream of tartar, and salt.
In the bowl of a stand mixer with the paddle attachment, beat butter on medium speed until smooth. Add the sugars and beat until light and fluffy, about 3 minutes.
Add the pumpkin purée and vanilla, and beat until well combined, scraping down the sides as needed.
With the mixer on low, slowly add in the flour mixture. Mix just until combined. Cover and chill for at least 30 minutes or up to 24 hours. (Do not skip this step. The dough won’t roll in your hands if it isn’t chilled.)
Scoop 1 to 2 tablespoons of chilled dough and roll into balls between your palms. Roll in the cinnamon sugar until well coated and place 3 inches apart on the prepared baking sheets.
Bake for 12 minutes or until puffed and golden on the edges. Let cool on the baking sheet for 5 minutes, then transfer to a wire rack and cool completely.
Make sure your light brown sugar is soft and moist for the best cookies. If your brown sugar has hardened, it’s an easy fix! I wrote a detailed post on how to soften brown sugar.
If the dough is not rolling into a ball, allow it to chill in the fridge longer. It should chill for a minimum of 30 minutes, or the dough will not be firm enough to roll. If your kitchen is on the warmer side, you might have to roll them in batches, keeping half of the dough in the fridge.
Unlike most snickerdoodles, this pumpkin snickerdoodles recipe doesn’t contain any eggs! The addition of the egg made the cookies more cakey than chewy. If you like your cookies on the fluffier side, you can add 1 large egg or 1 egg yolk to the batter. Just beat it into the butter mixture with the pumpkin puree. Then chill and bake as instructed.
For pumpkin cookies that spread a bit more and bake up more crispy on the edges, bake the cookies at 350F for 14 minutes.
The cookie dough can be chilled overnight, but do not roll the cookies into balls and coat with sugar until you are ready to bake.
Avoid overmixing the cookie dough, or the cookies will come out dense.