Beat the cream cheese, add yolks and chocolate. Finally, beat in the sugar and vanilla, don't overbeat. Fold in the egg whites.
For the crust, use chocolate wafers, grind them up with a little butter. Or use graham cracker type too. For the finish, whip some cream (no sugar) and "frost" the cake. Then sprinkle the whole thing with grated white chocolate.
Bake at 350° for 40-45 minutes in a spring form pan.