Preheat oven to 350 degrees. Line baking sheets with parchment paper.
Whisk together flour, cornstarch, baking soda, and salt in a small bowl and set aside.
In a large mixing bowl, using a handheld mixer, cream together the butter, granulated sugar, and brown sugar on medium speed until light and fluffy.
Add the vanilla and eggs. Cream until well combined, about 1 minute. Add flour mixture just until combined.
Add chocolate chips and mix until evenly distributed through the dough. Refrigerate dough for 1-hour minimum. (Don't skip)
Scoop out the dough, using a medium cookie scoop, and place 2 inches apart on prepared baking sheets. Do Not flatten. Using your fingers lightly tighten the bottom edge of the cookie where it sits on the baking sheet. (this helps them puff up more and not flatten as easily). If the dough looks
Refrigerate the dough between scooping out the next batch to keep it cold.
Bake in preheated oven for approximately 12-14 minutes or until the edges are beginning to brown. The center of the cookies will look slightly underdone in the center. Do Not overbake or they will dry out!
Cool for 10 minutes on the baking sheet. Transfer to cool completely on a wire baking rack. They will slightly deflate as they cool. Enjoy!