Use an electric mixer to cream the butter, add white and brown sugar, then mix until smooth and creamy. It is essential to achieve a soft cream before following the next step.
Add the egg and mix. The egg should be at room temperature; otherwise, it will break the butter emulsion, resulting in crispy and hard cookies. Next, add pumpkin puree and vanilla extract and mix to combine.
Mix the dry ingredients (flour, salt, baking soda, ground cinnamon, and pumpkin spice) in a different bowl. Then add them to the creamy batter. Use a spatula to combine; the result should be a stiff batter. Finally, fold in chocolate chips and mix.
Cover the bowl and let it chill in the fridge for at least 2 hours overnight. The chilling process is key to the flavor and texture of the cookies.
Before baking the cookies, preheat the oven to 350F and prepare at least two baking trays with baking paper. Scoop cookie batter into the prepared baking tray (I used a 1.25oz scoop), leaving 2 inches between each cookie. Lightly flatten the top of each cookie.
Bake the cookies for 15 to 16 minutes or until the edges are set and lightly golden. Keep an eye on the cookies while baking. Baking time may vary depending on your oven, so start checking around the 14-minute mark.
Once baked, let the cookies cool on the baking trays for a few minutes before transferring them to a wire rack to cool completely. This allows them to set and firm up a bit.