Preheat the oven to 375°F. Line a baking sheet with parchment paper.
In the bowl of a stand mixer fitted with the paddle attachment, add the butter, dark brown sugar, cane sugar, and vanilla extract.
Mix on low until combined and there are no butter chunks.
Add the milk, flour, salt, and baking soda in that order. Mix on low until combined.
Add the chocolate chunks and mix to combine. If you want to reserve some of the chocolate chunks for the top of the cookies, you can, but that part is optional.
Using your hands, form the cookies into 12 balls and place them on the prepared baking sheets, you'll have 6 cookies per sheet. If you reserved chocolate chunks for the top, you can add them now.
Bake for 15 to 17 minutes, or until golden brown on the bottoms.
Sprinkle with flaky sea salt after coming out of the oven.
Store in an airtight container for up to 7 days.