1- Whisk together 2 and 1/4 cups all-purpose flour, 1 teaspoon baking soda, 1 and 1/2 teaspoons cornstarch, and 1/2 teaspoon salt in a large bowl; set aside.

2- Whisk melted 3/4 cup unsalted butter, 3/4 cup packed brown sugar, and 1/2 cup granulated sugar in a medium bowl until smooth. Add 1 large egg plus 1 egg yolk, whisk until combined, then whisk in 2 teaspoons pure vanilla extract.

3- Pour the wet mixture into the dry ingredients and mix with a large spoon or spatula until a soft, shiny dough forms. Fold in 1 and 1/4 cups semi-sweet chocolate chips.

4- Cover dough tightly and refrigerate for at least 2 hours, or up to 3 days overnight works best for that perfect texture.

5- If dough has chilled longer than 2 hours, let it sit at room temperature for 15 minutes. Scoop into balls: about 3 scant tablespoons for extra-large cookies or 2 heaping tablespoons for medium-large ones. Shape them tall and lumpy, placing them 3 inches apart on lined baking sheets.

6- Bake for 13-14 minutes until edges are lightly browned and centers look soft. Cool on the baking sheet for 10 minutes before moving to a wire rack. For an extra touch, press more chocolate chips onto the warm cookies.

7- Store your finished cookies covered at room temperature for up to 1 week.