Heat the sugar in water until sugar is dissolved. Place 12 cored apple halves in this syrup and cook them gently until tender but not soft. Remove the apples carefully and set aside. Put remaining apples halves in the syrup and allow these to cook as with the first batch.
The syrup by now will have become thick. Pour it through a sieve and add just a pinch of salt.
Mix half of the apricot jam or marmalade with the liqueur and fill the apple halves with it. Stir the rest of the marmalade into the boiled apple syrup with the juice and grated rind of the lemon.
Place the apple halves in the form of a mound on a heatproof serving platter, round side up. Fill the spaces between the apples with the juice mixture and smooth over.
Slice the almonds and set aside.
Beat the egg whites until they hold a stiff peak. Fold in the powdered sugar. Spread this mixture over the mound. Dust the top of the mound with additional powdered sugar. Stick the almond halves here and there on the mound to make them look as much as possible like porcupine quills.
Put platter in a 350° oven which has been preheated for 15 minutes, and bake 15 minutes until lightly browned. Watch carefully. Almonds will burn quickly.