Step 1

Beat the butter, brown sugar, and egg on medium-high speed in a stand mixer fitted with the paddle attachment or using a hand mixer until very light and fluffy, about 5 minutes.

Step 2

Scrape down the sides of the bowl, then mix in the pumpkin, 1 tablespoon of the pumpkin pie spice, and vanilla, beating on medium-high speed until combined.

Step 3

Scrape down the sides of the bowl again, spoon in the flour, cornstarch, baking soda, and salt, and mix until just combined, about 1 minute.

Step 4

Cover the dough and chill it in the refrigerator for at least 1 hour and up to 1 day.

Step 5

Crank up the oven to 350°F (180°C) and line two rimmed baking sheets with parchment.

Step 6

Stir together the granulated sugar and the remaining 1 teaspoon of pumpkin pie spice in a small bowl.

Step 7

Shape the cookie dough into 1 ½-inch balls, roll them in the spiced sugar, and place them on the baking sheets, spacing them about 2 inches (5 cm) apart. Using your hand, gently flatten each ball slightly.

Step 8

Bake until the edges are set and the tops are juuuust beginning to turn golden brown, 10 to 15 minutes.

Step 9

Let the cookies cool on the baking sheets for 5 minutes before transferring to a wire rack to cool completely.