Preheat oven to 350 degrees F. Line a large baking sheet with parchment paper or a silicone baking mat; set aside.
In a large mixing bowl, whisk together the melted butter and sugars until well-combined.
1 cup butter, 1 cup light brown sugar, ¾ cup granulated sugar
Place three layers of paper towels on a plate, and place the pumpkin puree in the center of the paper towels. Gently press two more paper towels on top to blot up the excess moisture.
1 cup pumpkin puree
Add the blotted pumpkin, egg yolk, and vanilla to the mixing bowl. Mix in until well combined.
1 large egg yolk, 1 teaspoon pure vanilla extract
Add flour, baking soda, pumpkin pie spice, and salt, and mix in until just combined. Don’t over mix.
3 cups all-purpose flour, 1 teaspoon baking soda, 2 teaspoons pumpkin pie spice, ½ teaspoon salt
Use a 1.5 tablespoons (medium) cookie scoop to drop the dough onto the prepared baking sheet, about 2 inches apart on the prepared cookie sheet.
Bake for 10-15 minutes or until cookies are set around the edges but look slightly underbaked and soft in the middle.
Let the cookies cool for 5 minutes on the baking sheet, and then transfer to a wire cooling rack to cool completely.
Notes
Butter: I use salted butter in this recipe. If using unsalted butter, increase the salt to 3/4 teaspoon.
Light brown sugar: Feel free to use dark brown sugar if you prefer.
Pumpkin puree: Be sure to use pumpkin puree and not pumpkin pie mix. Pumpkin pie mix has sugar and spices already added to it.
Flour: Weighing the flour is the most accurate way to measure it. To get the weights, click on "metric" immediately above the ingredients. You can also sift it or stir it well to break it up, lightly spoon it into the measuring cup, and level.