Grease a baking tray (approx. 35 x 40 cm). Coarsely grate ##marzipan##. Knead flour, sugar, vanillin sugar, 1 pinch of salt, marzipan, butter in flakes and egg yolk first with a hand mixer and then briefly with your hands to form ##streuseln##.
Press 2/3 of the crumble onto the tray as a base. Spread with jam. Sprinkle the rest of the crumbles on top. Bake in the preheated oven (electric oven: 175°C/circulating air: 150°C/gas: level 2) on the lowest rack (gas: see oven manufacturer) for approx. 40 minutes
Leave to cool for about 5 minutes. Cut into diamonds (approx. 2.5 x 5 cm), leave to cool on the tray