Preheat the oven to 375°F.
Mix the brown sugar, white sugar, and butter until creamy.
Add the eggs and egg yolks, and vanilla extract, and mix well.
In a separate bowl, combine the flour, cornstarch, baking soda, baking powder, and salt.
Gradually add the dry ingredients to the wet ingredients and mix until combined.
Fold in the chocolate chips or chopped chocolate.
Scoop the dough onto a baking sheet and bake for 12-14 minutes or until golden on the edges.
