Preheat the ovent ot 350ºF. Line a baking sheet with parchment paper, and set aside.
Cream together the butter and sugar with a fork. Whisk in the egg white and vanilla until smooth.
Fold in the flour, corn starch, baking soda, salt, and chocolate chips.
Divide the dough in two and mound it in two piles on the parchment paper.
Bake for 12 minutes. If baking your dough as one single cookie, bake for 15 minutes. If you want to divide your dough into 4 cookies, bake for 9 minutes.