Melt chocolate and cream cheese together. Let cool. Soften gelatin with cold water for 1 minute, then add boiling water, stir until dissolved and clear. Let this cool while you start whipping the heavy cream and sugar. As cream starts to thicken, add gelatin. Continue to whip until stiff peaks form. Add 1/4 of the cream to the chocolate mixture and mix thoroughly. Then fold this into the remaining cream. Once you have it completed, spread this chocolate mousse onto the cake and refrigerate.