Preheat oven to 350 degrees F. Line a large baking sheet with parchment paper.
In a medium bowl, whisk flour, cornstarch, baking soda and salt. Set aside.
In a separate large bowl, with an electric mixer, beat butter and sugars until light and fluffy. Blend in egg and vanilla extract. Add flour mixture, mixing just until combined. Fold in chocolate chips.
Roll two heaping 1/2 cups cookie dough into a ball and place on a baking sheet. Press down on each dough ball to create a disk shape. If dough is very sticky, refrigerate dough disk for 10 minutes before baking.
Bake for 10 minutes (one cookie at a time, if using a small baking sheet), until edges are slightly golden brown.
Remove from oven and let cookies rest on baking sheet for 10 minutes. Transfer to a wire rack to cool completely.
Immediately after removing cookies from oven, dot with additional chocolate chips for a finished look. To add more chocolate chips to all the cookies, I recommend an extra 1/2 cup of chocolate chips.
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