I n a clean bowl with clean, dry beaters, beat 3 egg whites till stiff. C arefully fold the chocolate mixture into beaten egg whites until completely mixed. Carefully place the next cake layer on top of the filling. Repeat till cake is finished. Refrigerate till frosting is firm, four hours or overnight.
S ometimes it takes a long time to fold the chocolate mixture into the beaten egg whites.
Be gentle and patient - over vigorous stirring will make the fluffy whites lose volume.