In a light-colored saucepan, melt butter over medium heat. Cook, stirring, until golden brown bits form and it smells nutty, 5–8 minutes. Scrape into a large mixing bowl (get all the browned bits) and cool to room temp—slightly warm is fine.
In the bowl of stand mixer, add the cooled brown butter, brown sugar, and granulated sugar. Beat until light and fluffy, about 4 minutes.
Add the egg yolk, vanilla, and pumpkin and mix until smooth.
In a large mixing bowl, combine the flour, cornstarch, baking soda, salt, pumpkin pie spice, and cinnamon. Whisk to combine and sift.
Add the dry ingredients to stand mixer with the wet ingredients; stir just until combined. Add the chocolate chips and mix until evenly distributed.
Line a sheet pan with parchment. Use a cookie scoop to fill the sheet pan with cookie dough balls (not touching) and place in the freezer for at least one hour.
Transfer the frozen cookie dough balls to a labeled freezer bag.
To bake from frozen, bake on a parchment-lined sheet at 350°F for 15–18 minutes until edges are set and centers are slightly underdone.
To back from fresh (unfrozen), bake for 8-10 minutes
Notes
Freeze unbaked dough: Up to 3 months.
Baked cookies: Store airtight at room temp 3–4 days or freeze up to 2 months.
Rewarm: 300°F oven for 3–4 minutes brings back that just-baked texture.