Place the cake on a foil board or cake plate.
Dust your hands and the work surface with a little icing sugar and knead the marzipan until soft.
Roll out half the marzipan to fit the top of the cake and roll out the rest in strips to fit around the sides of the cake.
Brush the cake all over with the warmed apricot jam and then place the marzipan on top and around the cake.
Cover the cake with a clean tea towel and then leave in a cool place for at least one day.
To make the icing, lightly whisk the egg whites adding the sugar at intervals. Beat well until the icing reaches soft peaks. Add the glycerine if using and the lemon juice.
Spread icing all over cake either flat iced using a clean ruler or by forming soft peaks. Decorate with Christmas ornaments.
