In a stand mixer with the paddle attachment, beat on medium speed the butter, brown sugar and granulated sugar until no visible butter chunks remain. Add the eggs and vanilla and mix until just incorporated. Scrape down the sides of the bowl as needed.
In a large mixing bowl, whisk together the flour, cornstarch, baking soda and salt. Set aside.
Turn the mixer to low speed and slowly add in the dry ingredients until combined. Do not overmix.
Reserve about 3 tablespoons of chocolate chips for topping the cookies. Fold in the remaining chocolate chips.
Scoop out 16 (3-ounce balls) and loosely shape into rough, tall balls onto a baking sheet lined with parchment paper. Place dough balls onto the baking sheet, spacing them out about 4 inches apart. Top with additional chocolate chips if desired. Chill for 1 hour minimum.
Bake in a 350°F preheated oven for 15-16 minutes until edges are golden and centers look slightly underdone. You may need to rotate pans halfway through bake time. Cookies will continue to bake after taking them out of the oven.
As soon as the cookies come out of the oven, place a round cup or small bowl over each cookie and gently swirl it in a circular motion. This “scoots” the soft edges inward and shapes the cookie into a perfectly round circle.
Top with additional chocolate chips or flake salt, if desired.
Let cool on the baking sheet for 10 minutes before transferring them to a wire rack for further cooling and enjoy!