Place 1/2 cup pumpkin purée between several layers of paper towels and press firmly to blot out excess moisture until reduced to about 1/3 cup. This is the crucial secret that prevents cakey cookies and guarantees a chewy center!

In a large mixing bowl, whisk together melted butter, blotted pumpkin purée, brown sugar, and granulated sugar until glossy and smooth. Whisk in the egg yolk and vanilla extract until emulsified.

In a separate bowl, whisk together all-purpose flour, cream of tartar, baking soda, pumpkin pie spice, and salt. Fold the dry mixture into the wet dough with a silicone spatula just until no flour streaks remain. Do not overmix.

Cover the bowl with plastic wrap and chill the dough in the refrigerator for 35 to 45 minutes so it firms up enough to roll easily without sticking to your hands.

Preheat oven to 350°F (175°C). Line two large baking sheets with parchment paper. In a small shallow bowl, combine granulated sugar, ground cinnamon, and pumpkin pie spice.

Scoop 1.5 tablespoon dough balls (about 35g each). Roll into smooth spheres, then roll generously in the cinnamon sugar coating until completely covered. Place on baking sheets 2 inches apart. Lightly flatten the tops with the bottom of a drinking glass.

Bake for 10 to 12 minutes until edges are set and crackly with soft, puffed centers. Remove from oven and gently bang the baking sheet on the counter once to create signature crinkle ripples. Cool on the pan for 10 minutes, then transfer to a wire rack. Serve warm!