Step 1

In a saucepan, over low heat, melt butter. Stir in cocoa powder. Mixture will resemble a thick paste.

Step 2

Transfer chocolate mixture to a large mixing bowl. With mixer on low speed, add in powdered sugar and milk, alternating the two. Reserve a few tablespoons of milk. If frosting is thick, add in remaining milk. Add vanilla extract.

Step 3

Turn mixer to medium high speed and beat about 5 minutes, until frosting is smooth and creamy.

Step 4

Frost cake or cupcakes as desired.