Put flour, sugar, vanilla sugar, salt, almonds, egg yolk and bitter almond oil in a mixing bowl. Grate the raw marzipan mixture on a coarse grater. Add cold fat in flakes.
Knead everything into a smooth dough. Cover and let it rest in the fridge for about 1 hour. Roll out the dough on a floured work surface to a rectangle (approx. 40x35 cm). Roll out the lozenges (approx. 4.5x4.5 cm) with a dough wheel.
Place on a baking tray lined with baking paper. Brush with egg white and sprinkle thickly with flaked almonds. Bake in the preheated oven (electric cooker: 200 °C/ gas: level 3) for about 15 minutes.
Let it cool down on a cake rack. Dust with icing sugar. Makes about 45 pieces.