To the bowl of a stand mixer fitted with the paddle attachment or large bowl and electric handheld mixer, beat the butter on low speed until smooth, about 1 minute.
Add the sugars and beat on medium-high speed until creamed and well combined, about 2 to 3 minutes.
Stop, scrape down the sides of the bowl, and add the egg, vanilla, and beat on medium-high speed until light and fluffy, about 2 minutes.
Stop, scrape down the sides of the bowl, and add the flour, corn starch, baking soda, salt, and mix until just combined, about 30 seconds.
Add the chocolate chips and beat for a few seconds on low speed to incorporate.
Using a mini 1/2 tablespoon cookie scoop, form mounds and place them on a large plate or tray, lightly smoosh the mounds down a slight amount, cover with plasticwrap and refrigerate for at least 2 hours, up to 5 days.
Preheat oven to 350F, line a baking sheet with a Silpat Non-Stick Baking Mat, parchment, or spray with cooking spray. Place dough mounds on the baking sheet, spaced at least 1 inch apart; I bake 15 to 20 cookies per half sheet pan.
Bake for about 5 to 6 minutes, or until barely golden brown around the edges, even if slightly undercooked in the center, noting the tops will not be browned and will be pale.
Optionally, after cookies emerge from the oven, add a few more chocolate chips to the top of each cookie for visual appeal.
Allow cookies to cool on the baking sheet for 5 minutes before removing and transferring to a rack to finish cooling before serving with milk.
Notes
Store cookies in an airtight container at room temperature for up to 5 days or in the freezer for up to 3 months.
Alternatively, unbaked cookie dough can be stored in an airtight container in the refrigerator for up to 5 days, or in the freezer for up to 3 months, so consider baking only as many cookies as desired and save the remaining dough to be baked in the future when desired.