1. Add the butter to a light-colored saucepan and cook over medium heat until melted, foamy, and golden brown with a nutty smell. Remove from the heat and let it cool for 15 to 20 minutes.

2. Spread the pumpkin puree on paper towels and gently blot away excess moisture.

3. In a large mixing bowl, whisk together the cooled brown butter, brown sugar, and granulated sugar until smooth and glossy.

4. Add the blotted pumpkin puree, egg yolk, and vanilla extract, then whisk until fully combined.

5. In a separate bowl, whisk together the flour, cream of tartar, baking soda, cinnamon, pumpkin pie spice, and salt.

6. Add the dry ingredients to the wet ingredients and stir just until a soft dough forms.

7. Chill the dough for 20 to 30 minutes if it feels too soft to scoop.

8. Preheat the oven to 350°F and line baking sheets with parchment paper.

9. Stir together the sugar and cinnamon for rolling in a small bowl.

10. Scoop the dough into even balls and roll each one in the cinnamon sugar mixture.

11. Place the dough balls on the prepared baking sheets, leaving space between each one.

12. Bake for 10 to 12 minutes, until the edges are set and the centers still look slightly soft.

13. Let the cookies cool on the pan for 5 minutes, then transfer them to a wire rack to cool completely.