Whisk together flour, cocoa powder, baking soda, and salt. Once combined set aside.
Using a stand mixer or electric mixer beat softened butter with melted chocolate, sugar, and brown sugar. Once well combined add in the egg, vanilla extract, and milk. Add in dry ingredients and mix until well-combined.
Fold in white chocolate chips. Place dough in the fridge and allow to chill for at least 2 hours.
Pre heat oven to 350 degrees F. Prepare a baking sheet with parchment paper and roll out into 1 inch balls and place them on your baking sheet. Bake for 12-13 minutes. Allow to cool on pan for several minutes.