Courtesey of "The Splendid Table" cook book. DELICIOUS!! but very complex and time consuming. I'm posting the recipe as is but have used some substitutions in the past. I found you will need a few extra egg whites for the meringues. Also i substitute cooking sherry for the Mersala when it's not handy and have used almonds in place of the hazelnuts. The chocolate buttercream can be made up to 5 days ahead and both the meringues and zabaione cream can be made one day in advance. Good luck and good eating!