Grease an ovenproof dish (approx. 18 x 30 cm) and dust with flour. Separate the eggs. Mix 250 g butter, 250 g flour, 100 g sugar, 2 pinches of salt and egg yolk with the whisks of the mixer. Beat the egg whites until stiff, adding 100 g of sugar. Fold in the beaten egg whites.
Peel, quarter and core the apples. Cut quarters into slices. Mix with caramel spread.
Preheat oven (electric cooker: 175 °C/circulating air: 150 °C/gas: see manufacturer). Spread half the dough in the form. Add caramel apples and cover with the rest of the dough. Bake in the hot oven for approx. 1 hour (stick test!). Serve lukewarm or cold.