Preheat the oven to 350°F. Line sheet trays with parchment paper, set aside.
In a large bowl stir together the flour, cornstarch, baking soda, and salt, set aside.
In the body of a stand mixer with the paddle attachment cream the butter with the sugars for 3 minutes until light and fluffy.
Add the eggs in one at a time making sure the first one is fully mixed in before adding the next. Stir in the vanilla.
Add the dry ingredients and slowly stir them in until combined. Scrape down the sides as needed.
Reserve ½ cup of the chocolate chunks on the side. Add the remaining chocolate chunks and mix until just combined.
Portion the cookie dough into 18 portions, about 2.5 ounces each.
Roll the cookie dough between your hands to form a smooth ball. Place them onto the sheet trays 4 inches apart.
Top each cookie with the reserved chocolate chunks, about 3 chunks per cookie, and gently press them into the tops.
Bake for 12-13 minutes until the cookies are puffed up, they do not appear moist in the center and they start to very lightly brown along the edges.
Immediately sprinkle them with some flaky sea salt if using. Let them cool completely on the sheet tray.
If you’ve tried this recipe, come back and let us know how it was in the comments or ratings!