Melt butter in a light-colored saucepan over medium heat; whisk constantly until the butter foams, browns, and emits a nutty aroma. Transfer to a heatproof bowl and allow to cool for 15 minutes.

Spread the pumpkin puree onto a plate lined with three layers of paper towels. Press with additional paper towels to absorb excess liquid until the puree is thick and reduced to approximately 1/3 cup.

In a large mixing bowl, whisk the cooled brown butter with the brown sugar and 1/2 cup granulated sugar until fully combined and smooth.

Whisk in the egg yolk, maple syrup, and vanilla extract. Add the blotted pumpkin puree and stir until the mixture is homogeneous.

In a separate bowl, sift together the flour, cornstarch, baking soda, salt, and pumpkin pie spice.

Gently fold the dry ingredients into the wet ingredients using a rubber spatula until no flour streaks remain. Do not overmix.

Cover the dough and refrigerate for at least 30 minutes to allow the flour to hydrate and the butter to firm up.

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

Combine the rolling sugar and cinnamon in a small bowl. Scoop 1.5-tablespoon portions of dough, roll into balls, and coat thoroughly in the cinnamon-sugar mixture.

Place dough balls 2 inches apart on the baking sheets and bake for 10-12 minutes until the edges are set but the centers remain soft. Cool on the pan for 10 minutes before transferring to a wire rack.