In a large mixing bowl, combine the all-purpose flour, cocoa powder, granulated sugar, brown sugar, and salt. Mix well until all dry ingredients are evenly incorporated.
Add the softened butter and vanilla extract to the dry mixture. Using a hand mixer or spatula, blend until the mixture is crumbly.
Gradually add the milk, one tablespoon at a time, mixing until the dough reaches a smooth and creamy consistency. You may need to adjust the amount of milk based on your desired texture.
Fold in the white chocolate chips and red sprinkles until evenly distributed throughout the dough.
Transfer the cookie dough to an airtight container and refrigerate for at least 30 minutes to firm up before serving.