In a large bowl, use an electric mixer to beat the cream cheese and butter together. Beat in vanilla.
Add powdered sugar 1 cup at a time, alternating with tablespoons of cream and ¼ cups of cocoa. Use up all of the cocoa, and continue to add sugar and cream until you reach the consistency you desire.
Notes
Depending on how thickly spread you like your frosting, this will frost 18 to 30 cupcakes.