Melt the chocolate, butter and vanilla in a double boiler. When just smooth stir in the cream. Makes ONE serving. :-) Serve in the smallest mugs you can find to all your friends. Top with freshly whipped cream, made from left over cream, and a mini-marshmellow. WARNING: This stuff can kill you if you drink it too often. The Surgeon General recommends at most once a month for safe for consumtion. :D