Preheat Oven
Preheat your oven to 350°F (175°C). Line two baking sheets with parchment paper and set aside.
Mix Dry Ingredients
In a medium bowl, whisk together the flour, cocoa powder, baking soda, and salt. Set aside.
Cream Butter and Sugars
In a large mixing bowl, use a hand mixer or stand mixer to cream together the softened butter, granulated sugar, and brown sugar until light and fluffy, about 2-3 minutes.
Add Wet Ingredients
Add the egg, milk, vanilla extract, vinegar, and red food coloring to the butter mixture. Mix until well combined, and adjust food coloring if you prefer a deeper red.
Combine Wet and Dry Ingredients
Gradually add the dry ingredients to the wet mixture, mixing on low speed until just combined. Avoid over-mixing, as this can make the cookies tough.
Fold in White Chocolate Chips
Using a rubber spatula, gently fold in the white chocolate chips until evenly distributed throughout the dough.
Portion and Bake
Scoop tablespoon-sized portions of dough and roll them into balls. Place them on the prepared baking sheets about 2 inches apart. Press a few extra white chocolate chips on top of each cookie, if desired.
Bake and Cool
Bake for 9-11 minutes or until the edges are set but the centers still look slightly soft. Remove from the oven and allow the cookies to cool on the baking sheets for 5 minutes before transferring to a cooling rack.