Preheat oven to 410 degrees.
In a stand mixer, cream together cold butter, brown sugar and white sugar until creamy (about 4 minutes).
While butter and sugar is mixing, sift together the flour, cornstarch, baking soda and salt.
Add eggs one at a time to butter and sugar mixture, mixing well after each egg.
Add vanilla and mix.
Slowly mix in flour mixture until just combined to avoid over mixing.
Gently stir in chocolate chips and nuts if desired.
Drop oversized scoops of cookie dough onto cookie sheet. I prefer to use a baking stone, but any cookie sheet will work. I fit 6 cookies onto a sheet. Dough makes 12-15 large cookies.
Bake 9-12 minutes or until golden brown on top.
Remove from oven and let them rest for at least 10 minutes on the cookie sheet.
