Make the cake mix according to package directions about 2 days before making dessert.
Cut cake into 1 inch squares.
Line a large bowl with wax paper.Put some cake pieces into bowl. Melt chocolate and icing sugar together with hot water.Add to the melted chocolate the beaten egg yolks. Cool and then fold in 4 beaten egg whites.
Pour some of the the chocolate mixture over cake pieces...add more cake then more chocolate...keep repeating till all cake and chocolate is used up.
Cover with plastic wrap and refrigerate for 4 - 5 hours or more.(This allows chocolate to harden)
When ready to serve turn cake out onto a serving plate, peel off wax paper and cover with sweetened whipped cream.
You can decorate this "white mound of deliciousness" with mint leaves, shaved chocolate,drizzle it with a chocolate sauce...what ever you like or serve plain.