In a large mixing bowl or a stand mixer fitted with the paddle attachment, beat together butter and sugars on medium-high speed until light and fluffy.
Add the pumpkin puree, egg, and vanilla extract to the butter mixture and mix again on medium speed to incorporate.
In a separate mixing bowl, whisk together the flour, salt, baking soda, baking powder, and pumpkin spice together until combined.
Add the flour mixture and chocolate chips into the large mixing bowl with the sugar and butter mixture. Stir the mixture together until just combined. If using a stand mixer, mix on low speed until just combined! If mixing by hand, use a wooden spoon or spatula to combine the wet and dry ingredients together.
Cover the bowl of cookie dough with plastic wrap and chill for at least 30 minutes, or up to 24 hours.
Once the dough is chilled, preheat the oven to 350℉. Line two large baking sheets with parchment paper or silicone baking mats.
Roll the dough into balls, about 1.5 Tablespoons of dough each. Place the cookie dough onto the prepared baking sheet, spaced 2 inches apart. Using the back of a spoon, very slightly flatten the tops of the dough balls. (Without doing so, the cookies may not spread evenly.)
Bake for 10-12 minutes, or until the edges of the cookie dough are just set and beginning to brown.
Remove the cookies from the oven and place the baking sheets on a cooling rack. Let the cookies sit on the rack for 2-3 minutes before removing them from the baking sheet and allowing them to cool fully or enjoy warm.
Notes
Pumpkin Puree: Use canned, 100% pumpkin puree, not pumpkin pie filling. To use homemade pumpkin puree, it is crucial to drain off some of the liquid, to match the consistency of canned pumpkin puree. Place the pumpkin puree in a fine-mesh strainer lined with cheesecloth over a large bowl. Refrigerate for a couple of hours. Measure out ½ cup of the strained pumpkin puree to use in the cookie recipe.No Pumpkin Pie Spice? Replace it with 1 teaspoon of ground cinnamon, ¼ teaspoon of ground ginger, ¼ teaspoon of ground nutmeg, and a pinch of cloves for a close replica.Chocolate Chips: Feel free to substitute milk chocolate chips or white chocolate chips for semi-sweet chocolate chips. Use regular or mini-size chocolate chips. Egg-Free Modification: Replace the egg with a flax egg, by mixing together 1 tablespoon of ground flaxseed with 3 tablespoons of water and letting the mixture sit for 5 minutes before adding to the pumpkin cookie batter.Gluten-Free Modification: Use your favorite 1:1 gluten-free all-purpose flour blend in place of the all-purpose flour.Storage: Once your cookies have cooled completely, place them in an airtight container with a slice of white bread and store them at room temperature for up to 5 days. Alternatively, freeze the cooled cookies in an airtight container for up to 1 month.Freezing Cookie Dough: Prepare the dough as directed. Roll the cookie dough into 1-½ inch balls and place them onto a rimmed cookie sheet that has been lined with parchment paper. Place the tray into the freezer and freeze for 1 hour, or until solid. Transfer the cookie dough balls to a freezer-safe storage bag and store them in the freezer for up to 3 months. When ready to enjoy, bake the frozen cookie pumpkin chocolate chip cookie dough balls at 325 degrees F for 12-14 minutes, until just set.