Bakery-Style Chocolate Chip Cookies

In the bowl of a stand mixer fitted with a paddle attachment, cream the butter, brown sugar, and granulated sugar until combined and fluffy. Scrape the bowl well, then add the egg and vanilla with the mixer on low speed. Mix until well combined.
Scrape the bowl again and add the flour, cornstarch, baking soda, baking powder, and salt. Mix just until the ingredients are combined. Fold in the chopped chocolate and chocolate chips.
Scoop the dough onto a parchment-lined pan using a 2-ounce cookie scoop (about ¼ cup). Refrigerate the dough for at least 2 hours, preferably overnight.
Once the cookie dough has chilled, remove it from the fridge and allow it to sit at room temperature for about 15 minutes before baking. Line 2 baking sheets with parchment paper or a silicone mat and preheat the oven to 350°F.
Place the cookies onto the prepared pans, spacing them at least 2 inches apart.
Bake at 350°F for 12-14 minutes or until golden brown around the edges. Top the cookies with additional chopped chocolate pieces and chips while they’re hot. Allow to cool for at least 10 minutes. Finish with flaky sea salt if desired and enjoy!