Preheat the oven to 375°F and line 2 large baking sheets with parchment paper and set aside.
In a large bowl or stand mixer (highly recommend a stand mixer for this recipe) fitted with a paddle attachment, cream together the butter and sugar on medium speed for 2 minutes, scraping down the sides of the bowl halfway through.
1½ cups unsalted butter, 1 cup granulated sugar, 1½ cups light brown sugar
Add the eggs one at a time, mixing after each one just until the yolk is streaky throughout the dough.
2 large eggs, 1 teaspoon vanilla bean paste
Add the vanilla bean paste and mix just for a couple of seconds.
In a medium mixing bowl, whisk together the flour, baking soda, sea salt, and cornstarch. With the mixing beating at low (stir) speed, slowly add the flour mixture. If you have a flour shield for your mixer, I recommend using this as this recipe creates a lot of dough. Increase to medium speed and mix just until combined then remove from the mixer and use a rubber spatula to mix up any loose flour from the bottom of the bowl into the dough.
4 cups all-purpose flour, 1 teaspoon baking soda, 1½ teaspoons sea salt, 1 tablespoon cornstarch
Add the chocolate chips and mix at low speed just until combined, be careful not to overmix. You can finish mixing with a rubber spatula or with your hands until the dough is fully combined and the chips are evenly incorporated.
2 cups dark chocolate chips, 2 cups mini chocolate chips
Use a 1-cup measuring cup to portion out the dough, drop 2 of the dough balls on each prepared baking sheet and gently use your hands to press the cookies dough until they're about 1-inch thick and 5-inch across. Press additional chocolate chips into the top of the cookies and sprinkle with flaky sea salt before baking if desired.
1 tablespoon flaky salt
Bake the cookie sheets one at a time for 11 to 14 minutes, the edges will just be turning light brown. While the first batch bakes, use the second baking sheet to prepare the next batch.
Once baked, remove from the oven and allow to cool for 15 minutes before transferring to a wire rack using the parchment paper to transfer. Add fresh parchment paper and prepare the next batch. This recipe will make 8 cookies and 4 batches total.