Rinse the raisins, drain and soak in rum for about 30 minutes. Wash apples, quarter them, remove seeds and cut into slices. Separate eggs. Beat the egg whites and 1 pinch of salt until stiff with the whisks of the mixer. Whisk egg yolk with milk. Add flour, 50 g sugar and sour cream and mix to a smooth dough. Carefully fold the beaten egg white into the dough in 2 portions.
Preheat oven (electric cooker: 200 °C/circulating air: 180 °C/gas: see manufacturer). Heat an ovenproof pan (26 cm Ø) on the stove. Sprinkle 1 tablespoon of sugar evenly on the bottom of the pan. Spread apple slices close together. Add 2 tbsp. butter in small pieces and melt. Spread the dough over the apples. Drain the raisins and collect the rum. Sprinkle raisins on the dough. Bake at medium heat for about 2 minutes. Put the pan in the hot oven on the middle shelf, bake the slices of pancake for 10-15 minutes until golden brown.
Remove the sardines from the oven and sprinkle with 2-3 tablespoons of the rum collected. Melt 1 tablespoon of butter in small pieces on the edge of the pan until the slices of rum come off the edge of the pan. Place a large plate on the pan, turn it over and turn the sardines over. Dust with icing sugar and serve immediately.