Grab a medium bowl and whisk together the flour, pumpkin pie spice, cinnamon, baking soda, cream of tartar, and salt. Once it’s all mixed, set it aside for later.
In a larger bowl, use an electric mixer to beat the butter, granulated sugar, and brown sugar until smooth and fluffy (about 1 to 2 minutes).
Add in the egg yolk and vanilla, then mix in the pumpkin puree. Don’t forget to scrape down the sides so everything blends nicely.
Now, pour the dry mix into the wet mix and stir until just combined. Cover the bowl tightly and pop it in the fridge for about 30 minutes to chill.
When the dough is almost ready, preheat your oven to 350°F (177°C). Line two baking sheets with parchment paper or silicone baking mats.
Take the dough out of the fridge. Scoop about 1.5 tbsp of dough for each cookie and place them on the baking sheets, leaving some space between each scoop.
In a small bowl, mix together 2 tbsp of sugar and 1 teaspoon of cinnamon. Roll each cookie dough ball in this sweet coating, then set them back on the baking sheet.
Bake for 10 minutes, just until the cookies look set. Let them cool on the baking sheet for 10 minutes before moving them to a wire rack to cool completely.