Peel, quarter, core and cut apples into small pieces. Boil them up with lemon juice, liqueur and sugar. Simmer covered for about 5 minutes, stirring from time to time. Drain the compote and collect the juice. Cool down
Defrost the puff pastry slices side by side. Cut the cake into small cubes and sprinkle with approx. 100 ml juice. Coarsely chop the almonds
Place the slices of dough on top of each other, roll out to a rectangle (approx. 38 x 48 cm) on a little flour. Sprinkle with ground almonds. Spread the apples on top, leaving about 2 cm all around and about 10 cm free on one short side.
Sprinkle almonds and cake cubes on the apples. Brush the edges of the dough with water. Roll up the dough from the short side towards the wide free edge. Press the ends together slightly if necessary.
Line baking tray with baking paper. Place the strudel on the tray with the seam side down. Whisk the egg yolk and 1 teaspoon of water. Spread the strudel with it. Bake in the preheated oven on the 2nd rack from below (electric oven: 200 °C/circulating air: 175 °C/gas: level 3) for approx. 30 minutes. Dust with icing sugar. Serve warm with cream or ice cream