Heat oven to 375ºF. Line 5 half-sheet pans with parchment paper and set aside.
Sift together the flour, salt, and baking soda in a mixing bowl. In a seperate bowl, combine the egg, milk, and vanilla and bring to room temperature.
In the bowl of a stand mixer fitted with the paddle attachment, cream the butter, starting on low speed to soften it. Add the sugars. Increase the speed, and cream the mixture until light and fluffy. Reduce the speed back to low and add the egg mixture slowly. Increase the speed and mix until well combined.
Slowly add the flour mixture, scraping the sides of the bowl until thoroughly combined. Stir in the chocolate chips. Scoop onto the prepared pans, 6 cookies per pan. Bake for 13 to 15 minutes, checking the cookies after 5 minutes. Rotate the pan halfway through baking for more even browning.
Remove the cookies from the pans to a wire rack immediately. Once cooled, store in an airtight container.