Set the eggs and butter out to warm to room temperature.
prepare the Dry Mixture
In a large mixing bowl, whisk together the flour, cornstarch, baking soda, baking powder, and salt. Set aside.
prepare the Wet Mixture
In a separate large mixing bowl, use a hand mixer to mix the softened butter, light brown sugar, and granulated sugar. Start at low speed and increase to medium-high until the ingredients are completely mixed.
Add the vanilla and then the eggs, one at a time, mixing at medium speed until completely combined.
combine the Wet & Dry Mixtures
Gradually add the dry mixture, about a third at a time, to the wet mixture and mix by hand with a large spoon or spatula, folding in and mixing until they are completely combined to make the cookie dough.
Fold the chocolate chips into the cookie dough.
chill the Cookie Dough
Line two cookie sheets with parchment paper and scoop out 2 tablespoons of cookie dough and roll into smooth balls. Place each ball at least 2 inches apart on the cookie sheet. Twelve cookies should fit on each baking sheet. To get a perfectly smooth ball of dough and make this much easier and less messy, keep a bowl of ice water and some paper towels nearby to very slightly dampen and clean your fingertips and palms before rolling each cookie. This will keep the dough from sticking to your hands and allow you to roll a smooth ball of dough.
Place each baking sheet in the freezer for 10 minutes to chill before baking.
Alternatively, if you do not have room in your freezer for the cookie sheets, cover the bowl of dough with plastic wrap and allow to chill in the freezer for 30 minutes or refrigerator for 2 hours.
bake the Cookies
Preheat oven to 350° F.
Bake each sheet of cookies separately. Remove the first baking sheet from the freezer and immediately place on the middle rack of the oven and bake for 13 to 15 minutes or until the edges just begin to set but before they start to brown. The cookies will look slightly undercooked when taking them out of the oven. This is important to ensure a soft exterior and chewy middle.
Place the second sheet of cookies in the freezer and repeat the baking instructions.
Remove the cookies from the oven and allow to cool for 10 minutes.