Preheat the oven to 175 C and line a baking tray with a silicone mat.
In a microwave-safe mixing bowl, melt the butter, taking care not let it get too hot. If a few lumps remain, stir to melt them completely rather than overheat the mixture.
Add the sugars. Stir very well to combine. Stir in the vanilla and milk, mixing till combined. I used a silicone spatula to stir throughout the recipe, a balloon whisk works too.
Finally, sift the flour, baking soda and salt into the bowl. Fold gently to make a soft dough that may appear a little greasy because of the melted butter. It might seem like there's too much flour at first but the dough will come together. Finally, fold in the chocolate chips, dispersing them evenly through the dough.
Form 12 equal dough balls (1.5 tablespoons of dough each; I usually get between 12 and 14 cookies from this recipe), using a cookie scoop or your hands. These cookies don't spread a lot, which is why I don't chill the cookie dough.
Bake for 10 to 12 minutes until the edges are browned but the cookies are still quite soft in the middle, rotating the tray as needed to ensure evenly baked cookies. They will firm up and harden further as they cool so if you over bake them, they lose their signature chewy centers.
If the cookies are very puffy, tap the tray firmly on the counter as soon as it's out of the oven to help the cookies flatten, or press down gently with the back of a spoon. While the cookies are still hot, press a few more chocolate chips on top for extra melty goodness!
Once the cookies have cooled, transfer them to an airtight tin and store at room temperature for 4 to 5 days. Happy baking!