In a large mixing bowl, whisk the flour, cocoa powder, baking soda and salt together then set aside.
Using a handheld or stand mixer (see notes if you don't have either), beat the butter, brown sugar and granulated sugar on high speed until creamy for about 1-2 minute. Next add in the egg, milk, vanilla extract & the food coloring then beat till well combined then turn off the mixer.
Add in the dry ingredients into the wet ingredients. Turn the mixer on low speed and slowly beat until a very soft dough is formed. Incase you need to add in more food color feel free to do so at this point. Finally, add the chocolate chips & beat them in. You will end up with a sticky dough.
Cover the dough with plastic wrap and allow to chill in the refrigerator for at least 2 hours or overnight. Once chilled, allow the dough to sit at room temperature for at least 15 minutes before rolling into balls and baking because the dough will have hardened.
Preheat your oven to 180°C. Line two large baking trays with parchment paper or silicone baking mats. Set aside.
Using a tablespoon, scoop a heap of the cookie dough and roll into a ball. Arrange them on the baking trays lined with parchment paper then bake for 11-13 minutes each tray. Bake into batches! Once baked, you can stick a few more chocolate chips on tops of the warm cookies.
Let the cookies cool for about 5 minutes before transferring them to a wire rack for them to cool down completely.
Serve & enjoy.