In a large bowl, whisk together the flour, cornstarch, baking powder, baking soda, and 1.5 teaspoons of sea salt. Set aside.

In another large mixing bowl, cream the butter and sugars together with a hand mixer or stand mixer until light and fluffy, about 3-4 minutes.

Add the vanilla extract, and then add the eggs one at a time, mixing well after each addition.

With the mixer on low speed, gradually add the dry ingredient mixture to the wet ingredients. Mix until just combined.

Fold in the chocolate chips, chocolate chunks, and any chocolate shavings created during the chopping.

Place the cookie dough into an air-tight container and chill for at least 3 hours, preferably 24 hours. For the best flavor, chill the dough for 72 hours.

When ready to bake, preheat your oven to 350 degrees Fahrenheit (175 degrees Celsius). Line baking sheets with parchment paper or baking mats.

Using a standard-size cookie scoop (1.5 tablespoons), place dollops of dough onto the prepared baking sheets, about 12 cookies per sheet.

Sprinkle a little sea salt on top of each dough ball, then bake in the oven for 10-12 minutes or until the edges are golden brown and the tops are lightly golden.

The centers should look a little soft but not doughy.

Remove from the oven and allow to cool on the baking sheets for about 5 minutes before transferring to a wire rack to cool completely.