Cream together brown sugar, white sugar, and room temperature unsalted butter
Beat in whole eggs and egg yolks
Mix in vanilla extract
In a separate bowl, combine all-purpose flour, cornstarch, baking soda, baking powder, and salt
Fold dry ingredients into wet ingredients
Fold in semi-sweet chocolate chips or chopped chocolate
Bake at 375°F for 12-14 minutes or until golden on the edges
