Brown the butter in a skillet until lightly browned and smells nutty.
Transfer to a heat safe bowl and cool a bit.
Cover and chill in the fridge until solid, 2 hours or make a day ahead to save time.
Beat chilled butter in a mixer.
Add sugars and beat
Add egg, yolk and vanilla to combine.
On low, add flour, cornstarch, baking soda and salt.
Add milk.
Add chips and chill dough 2-3 hours.
Preheat oven to 350 and let dough sit on counter a few minutes until easier to scoop.
Scoop 1 1/2 T. of dough for each cookie onto parchment lined cookie sheets. Add a few extra chips for a prettier look on the outside of each dough ball.
Bake 10-12 mins and cool on sheets.
After 5 minutes, transfer cookies to a cooling rack to cool completely.
*Option for LARGE cookies:
Scoop 5 ounce mounds, chill and bake 17-20 mins at 350.