Preheat the oven to 375°F. Line two baking sheets with silicone baking mats or parchment paper.
In a large bowl, using a mixer, cream together the butter and sugars for 1 minute. Add the eggs and vanilla and beat just until combined once the eggs are added, you don't want to over mix.
Add the flour, baking soda, salt and cornstarch and pulse on low. I like to slowly mix in the chocolate chips with the last cup of flour. Again, do not over mix. If the dough is too stick add an extra Tablespoon or two of flour. Refrigerate dough for 30 minutes if time allows.
Using a large cookie scoop (about 3 Tablespoons), scoop the cookie dough onto the baking sheet about 2-3 inches apart. Place extra chocolate chips on the top of the cookies if desired.
Bake for 8-10 minutes, or until the tops are barely golden brown. Allow cookies to set on pan for 2-3 minutes, and then remove to a cooling rack.