Begin by melting the unsalted butter in a microwave-safe bowl, which should take about 30-40 seconds. Allow it to cool for a few minutes until it's just warm but not hot to the touch.

While the butter cools, preheat your oven to 350°F (175°C). Line your baking sheets with parchment paper.

In a medium mixing bowl, whisk together the all-purpose flour, cornstarch, baking soda, and fine salt until evenly combined.

In a separate large bowl, whisk the melted butter with the packed light brown sugar and granulated sugar until the mixture is smooth and creamy.

Gradually incorporate the dry ingredient mixture into the wet ingredients, mixing gently with a spatula until just combined.

Fold in the mini or chopped chocolate chips carefully, ensuring they are evenly distributed throughout the dough.

Scoop the dough into a piping bag, cut a small tip at the end and pipe small dollops onto the prepared baking sheets.

Place your baking sheets in the preheated oven and bake for 6-8 minutes. You'll know they are ready when the edges are lightly browned while the centers remain soft.

Once baked, transfer the cookies to a wire rack and let them cool for a few minutes.

If desired, while the cookies are still warm, press a few additional chocolate chips on top of each cookie and sprinkle with flaky sea salt.