Combine melted butter, brown sugar and granulated sugar in a large bowl and whisk vigorously for about two minutes.
Blend in vanilla extract, egg, and egg yolk, whisking until the batter is smooth and pale.
Gently fold in flour, baking soda, corn starch and salt just until the ingredients are evenly mixed.
Stir in the chocolate chips evenly into the dough.
Using about ¼ cup for each cookie, shape the dough balls smooth with your hands, then place on parchment-lined baking sheets and chill in the fridge for one hour or freeze for thirty minutes.
Preheat the oven to 325°F (163°C).
Arrange chilled dough balls on a lined baking tray with at least three inches spacing between each.
Bake the cookies for 12 to 15 minutes, removing them when the edges turn golden and centers still look slightly underdone.
Let the cookies cool on the tray for 5 minutes before transferring to wire racks to cool completely.
Store your cookies in an airtight container to keep their freshness for up to five days.
