Melt Butter & Mix Dry Ingredients: First melt your butter. Let it cool down a little while you prepare the ingredients. In a small mixing bowl, whisk together the 1 cup plus 2 tablespoon all-purpose flour, ½ teaspoon cornstarch, ½ teaspoon baking soda, & ½ teaspoon kosher salt and set aside.
Mix Wet Ingredients: In a large mixing bowl, whisk together melted 6 tablespoon unsalted butter with ⅓ cup light brown sugar & ¼ cup granulated sugar until well combined (30 seconds to a minute). Add 1 large egg & 1 teaspoon vanilla extract & whisk in very well. Scrape bottom and sides of bowl and give it another whisk.
Combine dry ingredients with wet: Add the dry ingredients to the wet ingredients and mix just until combined. Fold in ½ cup mini chocolate chips. Reserve a few for adding to cookies right before baking.
Scoop cookies: small portions of dough, using slightly less than 1 tablespoon per cookie (about 15–17 grams each). Roll into smooth balls and place on a parchment-lined baking sheet.
Chill the rolled dough balls uncovered for at least 30 minutes, or up to overnight.
Preheat the oven to 350°: When ready to bake, preheat the oven to 350°F. Bake the cookies directly from the refrigerator for 8 minutes, until the edges are set and the centers still look soft.
Let cool briefly on the baking sheet before transferring to a wire rack.