Preheat oven to 350°F. Grease 3X9-inch cake pans, line with parchment paper and grease the parchment paper. (If there is anything I've learned in baking is always grease the parchment paper).
Whisk the flour, cornstarch, baking soda, and salt together in a mixing bowl.
Use a stand mixer fitted with a paddle attachment and beat the butter, brown sugar, and granulated sugar together on a medium-high speed until smooth. This took about 5 minutes. Add the eggs individually followed by the vanilla extract. Make sure it's evenly distributed.
Slowly add bowl of dry ingredients to the bowl of wet ingredients. Mix on a low setting until evenly combined. Then add the chocolate chips. The dough will be VERY thick and sticky.
Divide cookie dough between the pans and press down to make flat and even.
Bake for 20 minutes or until the cake layers are lightly brown on top and a toothpick inserted in the center comes out mostly clean. You'll probably get melted chocolate chip on there and that's fine.
Let completely cool.