Knead marzipan, hazelnuts and 3 tablespoons of Calvados. Wash apples, cut off lid, cut out core. Sprinkle all cut surfaces of the apples with lemon juice. Pour marzipan mixture into the apples.
Press the leftovers onto the upper cut surfaces and place in ovenproof moulds. Separate the eggs for the cream. Beat the egg whites until stiff, pour in 25 g sugar. Cream egg yolks, 4 tablespoons of Calvados and 75 g sugar.
Stir in cream and flour. Carefully fold in the beaten egg white. Pour the dough over the apples, place the apple lid on top. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for approx. 25 minutes.