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 (I highly recommend a stand mixer for this recipe) fitted with a paddle attachment, cream together the ¾ cup salted butter, ½ cup granulated sugar, and ½ cup granulated sugar at medium speed for 2 minutes, scraping down the sides of the bowl halfway through.
¾ cup salted butter, ½ cup granulated sugar, ¾ cup light brown sugar
Add 1 large egg and mix just until the yolk is streaky throughout the dough.
1 large egg, 1 teaspoon vanilla extract
Add 1 teaspoon vanilla extract and mix just for a couple of seconds.
In a medium mixing bowl, whisk together 2 cups all-purpose flour, 2 tablespoons powdered milk, 1 tablespoon cornstarch, ½ teaspoon baking soda, and ¾ teaspoon sea salt. 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.
2 cups all-purpose flour, ½ teaspoon baking soda, ¾ teaspoon sea salt, 1 tablespoon cornstarch
Add all but a ¼ cup of the 2 cups mini 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 mini chocolate chips
Portion the dough out into teaspoon-sized portions (5g each) for tiny cookies or tablespoons (10g each) for mini cookies, placing them at least ¼-inch apart on each prepared baking sheet. Press additional chocolate chips into the top of the cookies.
Bake the cookie sheets one at a time for 5 to 6 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 a couple of minutes before transferring to a plate or wire rack. Add fresh parchment paper and prepare the next batch.