Melt butter and chocolate in double boiler over low heat. Stir with wooden spoon until mixture is melted, but not hot. Mixture should be body temperature. Transfer chocolate/butter mixture to bowl.
Whip eggs and yolk at high speed with electric mixer. Pour mixture on top of butter/chocolate mixture, but do not mix in yet.
Put egg whites in clean bowl; whip until soft peaks form.
Add whipped egg whites to chocolate mixture; gently fold in with rubber spatula. Do not over-fold.
Spray two 9 x 5-inch (about) bread pans with nonstick cooking spray. Gently divide mixture between pans. Set each pan in larger pan; add water to larger pan to within one-half inch of top to create water bath.
Bake at 300° F for 60 to 70 minutes or until top looks dry (but top should not crack), and cake does not wiggle in pan. Cool 15 minutes. Invert pans onto serving plates.
After cooling, but while still warm, cut in thin slices. Prepare white chocolate sauce, and spoon onto individual serving plates. Put slices of cake over sauce. Garnish with fruit as desired.
This dessert is best served warm, but also can be served at room temperature.
NOTE: Cake also may be served warm or at room temperature with hot-fudge sauce, fresh strawberries and/or kiwi.
Combine chocolate and cream in small saucepan set in larger pan filled to within 1 inch of the top with water to create stove-top water bath. Gently cook over medium heat until mixture reaches body temperature, stirring occasionally. Remove from heat; strain through fine sieve to remove any lumps.
Makes: 14 to 16