Begin by squeezing out excess juice from the pumpkin puree using paper towels to achieve a chewier texture.
In a mixing bowl, cream together tahini, sugars, pumpkin puree, and vanilla extract until well combined.
Add flour, pumpkin pie spice, cinnamon, baking powder, salt, and cream of tartar to the mixture, stirring until just combined. Avoid overmixing.
Cover the dough and chill it in the fridge for at least 30 minutes.
Preheat the oven to 350°F and line a baking sheet with parchment paper. Prepare the cinnamon and sugar coating in a small bowl.
Scoop the chilled dough using a double cookie scoop, roll it into balls, and coat generously in the cinnamon and sugar mixture.
Flatten the dough balls slightly before placing them on the baking sheet. Optionally, sprinkle more cinnamon and sugar on top.
Bake for 12-15 minutes, then allow the cookies to cool slightly before transferring them to a cooling rack.