Instructions: In a mixing bowl, whisk together flour, cornstarch, baking powder, baking soda, and salt, then set aside. In a separate mixing bowl, mix the sugars and butter until fluffy. After scraping the side of the mixing bowl, add the egg, egg yolk, and vanilla, then continue whisking for two minutes. Gradually add the dry ingredients until fully mixed and smooth. Fold in 1 cup of the chocolate chunks. Let the cookie dough sit in the refrigerator for 30 minutes. Spoon out about a cup of cookie dough and form into a ball 2-3” in diameter Cover a baking sheet with parchment paper and place the dough balls 2” apart. You can bake them as dough balls or form the dough into a flatter cookie shape. Bake at 350º F for 15 minutes. Let cookies rest on baking sheet for 10 minutes and then transfer to a backing rack.
