Preheat oven to 400 degrees. In a large mixing bowl, cream together butter, brown sugar, and sugar for at least 4 minutes, scraping down the sides of the bowl often.
Add eggs and vanilla and mix for 1 minute longer.
Stir in cake flour, all-purpose flour, cornstarch, baking soda, and salt just until mixed. Fold in milk chocolate chips.
If you have a digital scale, weigh each ball of dough to be between 5-6 ounces. Once you decide on a weight, keep it consistent to the cookies bake evenly. Place on parchment paper lined baking sheet. Light colored baking sheets work best. Dark colored baking sheets hold too much heat and can burn the bottoms of the cookies.
Bake for 9-12 minutes, watching carefully. Let sit for at least 10 minutes to allow the center of the cookie to set up.