I never make this the same way twice, but here’s the overall pattern:
Melt 1 c chocolate chunks or chips or chopped chocolate. Let cool slightly.
Beat 1 c soft butter (no margarine) until fluffy. Add 1/4 c cocoa powder and gradually beat in 3 c powdered sugar. Beat in the melted chocolate and some vanilla. If the frosting is too thick, add some cream. Too thin? Add a little more powdered sugar.