Preheat oven to 350°
Line baking trays with parchment paper.
In a small bowl, combine flour, cornstarch, baking soda, and salt. Mix.
In a large bowl, combine butter, brown sugar and granulated sugar. Mix until combined.
Add in the egg and vanilla to butter and sugar mix. Mix well.
Now combine in the flour mixture. Mix thoroughly.
Fold in the chocolate chips.
Measure dough into 1/2 cup portions using a measuring cup. Roll into cookie dough balls. Leave adquate spacing for large cookies. ex. 3 per tray.
Bake 1 tray at a time, for about 15-20 minutes. Cookies will have a slight crunch on the outside but soft/dough but cooked through on the inside!