Preheat the oven to 350F (180C) degrees. Line baking sheets with parchment paper or silicone baking mats.
Place a double layer of paper towel to a small. Add in the pumpkin. Squeeze out the excess moisture in the pumpkin using the paper towel. Do this a few times to really remove the liquid.
In a medium bowl, whisk together the flour, spices, baking soda and salt.
In a large bowl beat the butter and sugars until fluffy. Then mix in the egg yolk, vanilla and pumpkin that you've squeezed the moisture out of.
With the mixer on a low speed, beat in the flour mixture about ½ at a time until combined.
Stir in 1 cup chocolate chips.
Spoon the dough into balls about 1 - 1.5 tablespoons in size (I use a cookie scoop). Place 2 inches apart on the lined cookie sheets. Flatten the dough balls down so that they're about ⅓ - ½ inch thick. If the dough is too sticky to form into balls, cover the bowl and refrigerate for 30-60 minutes, or overnight.
Bake 1 sheet at a time in the preheated oven for 8-10 minutes, or until the tops look set. Remove from the oven and place a few extra chocolate chips on top of each cookie from the remaining ¼ cup.
Cool cookies on the cookie sheet for at least 10 minutes, then transfer to a cooling rack to continue cooling.