Combine graham cracker crumbs, sugar and melted butter. Press on bottom and sides of a greased 0 cm springform pan. Combine pudding mix, sugar and milk in saucepan. Add chocolate. cook and stire over medium heat until mixture comes to a full boil. Remove from heat. Cover surface with waxed paper and set aside. Beat cream cheese until fluffy. Beat in yolks, vanilla, salt and pudding. Fold in egg whites. (Odd. Says nothing about beating the egg whites first. Hm. Well, I would.) Pour over crumbs in pan. Bake on lowest rack at 220ºC for about 35 minutes or until center is set lightly when touched. Cool 4 hours. Spread top with sour cream.