Line two flat baking sheets with parchment paper and set aside for now
Combine 8 tablespoons of melted butter with 1/2 cup of brown sugar and 1/4 cup of granulated sugar in a large bowl
Add a large egg, an egg yolk and 2 teaspoons of vanilla extract and whisk to combine
In a separate bowl, combine 1 1/3 cups of all-purpose flour, 2 teaspoons of cornstarch, 1/2 teaspoon of baking soda and 1/4 teaspoon of salt and then add to the remaining ingredients
Mix until just combined
Fold in 3/4 cup of chocolate chips and mix to incorporate
Form all of the dough into heaping teaspoons of dough, form into small round balls and place them on a parchment line plate
Place the dough into the freezer and preheat your oven to 350 degrees
Once the dough is quite firm and your oven is preheated, transfer the chilled dough onto your parchment lined baking sheets leaving about an inch between them
Bake in a 350 degree oven for 5-7 minutes or until the edges are just set
Transfer the baking sheet onto a cooling rack and allow the cookies to cool for several minutes before enjoying
Store leftovers in an airtight container at room temperature, in the refrigerator or freezer