Cut the marzipan into small pieces. Mix flour and baking powder, sieve it on a work surface and press a depression in the middle. Pour egg and bitter almond oil into the hollow. Sift 100 g icing sugar over it.
Spread soft fat and marzipan pieces on the flour rim. Knead into a smooth dough with your hands. Cover and put in a cool place for about 2 hours. Quarter the dough and form into 4 rolls on a floured work surface.
Cut each roll into 14 pieces. Form small rolls from each piece and bend them into croissants. Spread the croissants on two baking trays lined with baking paper and bake them one after the other in a preheated oven (electric range: 200 °C/ gas: level 3) for 10-15 minutes until golden brown.
Let the croissants cool down. For the icing, mix rum, 2 tablespoons of water and remaining icing sugar to a thick icing. Spread the icing on the croissants and sprinkle with chocolate flakes. Leave to dry.
Results in about 56 pieces.