In a medium mixing bowl, whisk together the all-purpose flour, unsweetened cocoa powder, baking soda, and salt until well combined and no cocoa lumps remain. Set aside.
In a large mixing bowl, use an electric mixer to cream the softened butter, packed brown sugar, and granulated sugar on medium speed until smooth and creamy (about 2 minutes).
Beat in the egg, milk, vanilla extract, and red food coloring until the mixture is vibrant red and completely uniform.
Turn the mixer to low speed and gradually add the dry flour mixture to the wet ingredients. Mix just until the dry streaks of flour disappear. Do not overmix.
Use a rubber spatula to gently fold in the white chocolate chips.
Cover the bowl tightly with plastic wrap and chill the dough in the refrigerator for at least 1 hour.
When ready to bake, preheat the oven to 350°F (175°C) and line two baking sheets with parchment paper.
Scoop the chilled dough into 1.5 tablespoon-sized balls. Place them on the prepared baking sheets, leaving a few inches of space between each one.
Bake for 10-12 minutes. The cookies will look slightly underbaked and soft in the very center.
Allow the cookies to cool on the hot baking sheets for 5 minutes before carefully transferring them to a wire rack to cool completely.