Preheat the oven to 350°F. Line two baking sheets with parchment paper and set aside.
In a small mixing bowl, whisk the flour, salt, baking soda, and cornstarch. Set aside.
In a large mixing bowl, add the butter, milk, sugars, and vanilla. Beat until creamy.
Add about half of the flour mixture to the wet mixture and use a rubber scraper to combine. Add the rest and mix until combined.
Fold in all the chocolate chips and chunks.
Place large balls of dough (~1/4 cup each) on your baking sheet. Top each with extra chocolate and a sprinkle of salt. Want them to be extra big? Double the amount of dough and add a few more minutes to the baking time
Bake for 11-13 minutes, until they are baked to your liking. Sprinkle extra salt right when they come out of the oven.