Prep & Blot Pumpkin: Preheat oven to 350°F (175°C). Line two large baking sheets with parchment paper. Measure 1/2 cup canned pumpkin purée and spread onto a plate lined with 4 layers of paper towels. Press gently with additional paper towels to absorb excess moisture until the purée reduces slightly and feels dense.

Whisk Dry Ingredients: In a medium bowl, whisk together the flour, cream of tartar, baking soda, pumpkin pie spice, cinnamon, and fine sea salt. Set aside.

Mix Wet Ingredients: In a large bowl, whisk the melted cooled butter, packed brown sugar, and granulated sugar vigorously for 1 minute until glossy and smooth. Whisk in the blotted pumpkin purée, egg yolk, and vanilla extract until fully incorporated.

Combine Into Soft Dough: Pour the dry ingredients into the wet mixture. Use a silicone spatula to fold gently just until no dry flour streaks remain. Do not overmix. The dough will be soft, thick, and pliable.

Roll in Cinnamon Sugar: In a small shallow bowl, stir together the 1/3 cup granulated sugar, cinnamon, and pumpkin pie spice. Scoop 1.5 tablespoon portions of dough (approx. 35g each) and gently roll into smooth balls. Roll each ball generously through the cinnamon sugar coating until heavily frosted.

Bake to Golden Perfection: Arrange dough balls 2 inches apart on prepared baking sheets. Bake at 350°F (175°C) for 10 to 11 minutes. The edges will be set and lightly golden, while the tops will feature gorgeous crinkles with soft, puffy centers.

The Pan-Tap & Cool: Remove baking sheets from oven and immediately tap the pans firmly once or twice on the counter to settle the soft centers and enhance surface cracks. Let cookies rest on the hot pan for 8 minutes before transferring to a wire cooling rack. Enjoy warm!