Soak fish in cold water (at least 24 hours), change water regularly
Bring water to a boil in a suitable pot and simmer the fish for about 10 minutes. Drain and simmer in fresh water for another 10 minutes. Take the fish out, let it cool down a little and pluck it into pieces
Peel, wash and chop the potatoes and cook in salted water for about 20 minutes. Drain the potatoes. Add 1 tablespoon butter and milk and mash to puree. Season puree with salt and nutmeg
Clean, wash and cut the leek into thin slices. Peel and chop the garlic. Heat oil in a pan. Stir-fry the leek and garlic over medium heat for 4-5 minutes, add the fish. Season with pepper and lightly with salt
Wash the parsley, shake dry and chop the leaves into small pieces. Put the leek mix into a greased casserole dish and spread the puree on top. Melt 40 g butter, stir in breadcrumbs and half of the parsley. Spread butter crumbs on the puree and bake in a preheated oven (electric range: 175 °C/ convection oven: 150 °C/ gas: level 2) for approx. 30 minutes. Sprinkle with remaining parsley before serving
waiting time approx. 24 hours