Wash the apples, remove the core (potato peeler or apple cutter), peel them whole and cut into rings approx. 1 cm thick. Cover with sugar and rum and let it steep a little.
In the meantime, separate the eggs for the batter and beat the egg whites until stiff, set aside and use the remaining ingredients to make a thick pancake batter, fold in the egg whites by hand with the whisk.
Dip the marinated apple slices in the batter, turn them and fry them with a fork in a large, coated pan in plenty of hot clarified butter until golden brown. Drain well on kitchen paper and dust with icing sugar while it is still hot.