Chocolate Decadence

16 oz. semi-sweet chocolate
3/4 cup butter
3/4 cup powdered sugar
1 Tbsp flour
4 eggs, separated
1 cup sour cream
1 tsp vanilla

Melt chocolate and butter.
Gradually mix in powdered sugar and flour; remove from heat.
Blend in the yolks, one at a time.
Blend in the vanilla.
Beat the egg whites until stiff and fold into the chocolate mixture.

Place 1 cup of the mixture in another bowl.
Pour the remaining mixture into a lightly buttered 8" square cake pan.

Mix the sour cream with the reserved chocolate, and spread on top of the mixture in the pan.
Bake for 25 minutes at 375 degrees; It will not appear set.
Cool thoroughly, then chill for 6 hours. (Freezes well)