In a microwave safe bowl microwave chocolates and butter together in 30 second increments, stirring after each 30 increment until the mixture is melted and smooth.
Stir in vanilla.
Add powdered sugar to the bowl of a stand mixture fitted with a whisk attachment.
Pour the chocolate mixture into the powdered sugar while the mixer is running.
Add the milk a little at a time, add only as much as it needed to obtain a smooth and spreadable frosting.
Course: Dessert
Cuisine: American
Keyword: dark chocolate fudge frosting, dark fudge frosting recipe