In the bowl of a stand mixer or using a hand mixer and mixing bowl, use the paddle attachment to cream together the sugars and butter on medium speed until fluffy (about 3-4 minutes).

Add the egg and vanilla and mix on low speed until combined.

In a separate bowl combine the flour, cornstarch, baking soda, and salt.

Carefully add the flour mixture to the wet ingredients and mix on low speed until combined. Stir (or fold in) in the chocolate chips.

Shape the dough into balls about 1 1/2 inches in diameter. Place the dough balls on the baking sheet and place in the refrigerator for at least 30 minutes prior to baking.

After the dough chills, place in the oven and bake for 10-12 minutes. Remove the cookies from the oven when the cookies are lightly brown but still look soft in the middle.

Allow the cookies to cool for 2-3 minutes on the baking sheet then transfer to a cooking rack. Store in an airtight container.