Grease bottom only of oblong baking dish, 12 x 71/2 x 2 inches.
Beat cake mix, water, oil and egg in large mixer bowl on low speed until moist ened.
Beat on medium speed 2 minutes.
Pour batter into baking dish; spread evenly.
Micro wave uncovered 4 minutes; turn dish one half turn.
Microwave until wooden pick inserted near center comes out clean, 2 1/2 to 3 1/2 minutes.
(Parts of the cake will appear very moist, but these parts will continue to cook while standing.) Cool thoroughly.
Cut into 1inch squares.
Mix sugar, gelatin and salt in 2 quart casserole or bowl.
Gradually stir in milk.
Add chocolate.
Microwave uncovered to boiling, 4 to 5 minutes, stirring every 2 minutes.
Beat until mixture is smooth.
Gradually stir a small amount of the hot mixture into eggs.
Blend into hot mixture in casserole.
Stir in vanilla; cool.
Beat whipping cream in 4 quart bowl until very soft peaks form.
Fold in chocolate mixture; then fold in cake squares.
Spoon into dessert dishes.
Refrigerate until set, at least 2 hours.