Roughly grate the marzipan. Knead flour, baking powder, 100 g icing sugar, marzipan, fat in flakes, egg and flavour until smooth. Cover the dough and chill for approx. 2 hours
Line 2 baking trays with baking paper. Quarter the dough, form into 4 rolls on a little flour. Cut rolls into about 14 pieces each. Form each piece into a roll (approx. 6 cm) and bend into croissants. Put them on the trays. Bake in a hot oven (electric cooker: 200 °C/circulating air: 175 °C/gas: level 3) for 10-15 minutes. Let them cool down
Mix rum, possibly 2 tbsp. water and 250 g icing sugar. Brush the croissants with it and sprinkle with chocolate shavings. Leave to dry