Marinate the raisins in rum for a day. Mix all dry dough ingredients, add the remaining ingredients and knead to form a smooth dough. Let rise for about 30 minutes. Divide the dough into 12 portions, shape them into balls, roll out balls about 3 mm thick into oval dough sheets (20 cm long). Roll up tightly from the narrow side and shape the dough rolls into croissants. Place on a baking tray covered with baking paper. Cover with a cloth and let rise for another 20 minutes. Whisk a yolk with a little milk, spread it over croissants and bake in the preheated oven on the middle rack at 180 degrees for about 18 minutes. If you don`t like raisins, you can leave them out.