8 ounces salted butter, softened (2 sticks)
6 ounces brown sugar
4 ounces granulated sugar
1 teaspoon vanilla extract
2 eggs room temperature
16 ounces all-purpose flour
2 teaspoons cornstarch
1 teaspoon baking soda
1/2 teaspoon salt
10 ounces milk chocolate chips
In a stand mixer or using a hand mixer, cream the butter, brown sugar, and granulated sugar until light and airy, scraping down the sides of the mixer as needed. Don’t cut the time short on this step; it should take 3 to 5 minutes for the mixture to be fully creamed.
Add the vanilla and one of the eggs. Mix on low until the yolk is broken. Add the remaining egg and mix on low until the second yolk is broken. The eggs should not be fully incorporated into the creamed butter mixture at this time.
In a small bowl, mix the flour, cornstarch, baking soda, and salt.
Add the flour mixture to the creamed butter. Mix on low until just incorporated; do not overmix. The batter may resemble wet sand instead of a cohesive batter, but it will hold together if you compress a small ball of dough in your hands. Fold in the chocolate chips.
Form the cookie dough into 5.5-ounce balls. Press each ball into a disk about 1/2 inch thick.
Cover the cookies and refrigerate overnight or for at least 1 hour.
Preheat the oven to 350°F. Place the chilled cookies on a parchment-lined baking sheet and bake until the cookies are golden brown, about 14 to 16 minutes. Remove the cookies from the oven and let them cool in the pan for 5 minutes.