In a large mixing bowl, use an electric mixer to briefly beat butter until smooth and creamy.

Add sugars and beat until light and fluffy.

Add eggs, one at a time, stirring well after each addition.

Add vanilla and stir to combine.

In a separate, medium mixing bowl, whisk together flour, cocoa, cornstarch, baking soda and salt.

Gradually add dry mixture ingredients to the wet in several parts, stirring on medium speed after each addition until flour is completely incorporated. Be sure to scrape the sides and bottom of the bowl with a spatula to incorporate all ingredients.

Add chopped chocolate and 1 cup mini chocolate chips and stir to combine.

Pour 130g mini chocolate chips into a small bowl. Scoop dough by 100g and form into a ball. Dip the top of the cookie dough ball into the chocolate chips, coating the top. Scoop all cookie dough and place on a cookie sheet. Place in the freezer for 20 minutes.

While cookie dough is freezing, preheat the oven to 190C and line baking sheets with parchment paper.

After 20 minutes, remove cookie dough from the freezer and place on prepared baking sheets, spacing cookies at least 2” apart. (After 20 minutes in the freezer, any unbaked cookie dough should be tightly covered and moved to the refrigerator.)

Transfer to center rack of preheated 190C oven and bake for 11-12 minutes, until cookie is cooked through.

Immediately sprinkle with flaky sea salt, if desired. Allow to cool completely on the baking sheet (cookies will be quite fragile and seem underdone before they’ve cooled completely!) before enjoying!