Place pumpkin puree in a small saucepan over medium heat and cook, stirring frequently, until reduced to about 1/2 cup; set aside to cool.
In a medium bowl, whisk together the flour, cornstarch, baking soda, and salt.
In a large bowl, cream together the softened butter, brown sugar, and granulated sugar until light and fluffy.
Add the cooled pumpkin puree and vanilla extract to the butter mixture and mix until fully incorporated.
Gradually add the dry ingredients to the wet ingredients until just combined.
Fold in the chocolate chips.
Chill the dough for at least 30 minutes to ensure a better texture.
Preheat oven to 350°F (175°C) and line a baking sheet with parchment paper.
Scoop rounded tablespoons of dough onto the prepared sheet.
Bake for 10-12 minutes until the edges are set but the centers remain soft.
Cool on the baking sheet for 5 minutes before transferring to a wire rack.