Melt unsalted butter in a saucepan over medium heat, swirling until golden brown flecks form and aroma is nutty (4-5 minutes). Pour into a bowl and let cool for 15 minutes.

Spread pumpkin puree onto 4 layers of paper towels, pressing gently with additional paper towels to absorb excess moisture until reduced to 1/4 cup concentrated paste.

In a large bowl, whisk cooled brown butter, brown sugar, granulated sugar, blotted pumpkin puree, egg yolks, and vanilla extract until smooth and glossy.

In a separate bowl, whisk flour, cream of tartar, baking soda, salt, cinnamon, and pumpkin pie spice. Fold dry mixture into wet ingredients until a soft dough forms.

Cover and refrigerate dough for 30-45 minutes to firm up.

Preheat oven to 350°F (175°C) and line two large baking sheets with parchment paper.

In a small bowl, whisk 1/3 cup sugar and 1 tbsp cinnamon.

Scoop 2-tablespoon portions of chilled dough, roll into balls, then roll generously in cinnamon sugar until heavily coated.

Place balls 2 inches apart on prepared sheets. Bake for 10-12 minutes until edges are set and tops are crackled.

Firmly tap the hot baking sheet against the counter 2-3 times to create crinkles. Cool on pan for 10 minutes before transferring to a wire rack.