In a large mixing bowl using a hand or stand mixer, combine butter, white sugar and brown sugar
Add in vanilla and egg and mix until incorporated
Slowly add in flour, baking soda and corn starch and mix until soft, thick dough forms
Add in chocolate chips and stir until just combined
Refrigerate 1 hour or longer (Don't skip this step!)
Preheat oven to 350 F and spray a baking sheet with nonstick cooking spray or use a non-stick silicone baking mat
Once dough is thoroughly chilled, roll or scoop into 1 1/2-2 inch balls and place an inch or more apart
Bake for 10-11 minutes. *Cookies will appear undercooked when first removed from the oven. Do not cook any longer - the cookies will continue to set while left to cool on the cookie sheet.
Allow to cool at least 10 minutes before serving. Enjoy!