For the puree, peel and wash the potatoes and cut them into pieces. Cover and cook in boiling salted water for about 20 minutes.
For the filling, wash parsley, shake dry, pluck leaves and chop finely. Cut half of the crab meat into smaller pieces if necessary. Mix with cream cheese and parsley, up to 1 tablespoon. Season with pepper.
Rinse fish and pat dry. Cut the fillets in half. Spread the cream cheese on the fish, fold it up and press it down a little. Season with salt and pepper and turn the filled pieces in flour.
Heat the oil in a large coated pan. Fry the fish for 5-6 minutes on each side.
Meanwhile peel and finely chop the garlic. Heat up with milk and 50 g butter in a small pot. Drain the potatoes, add the milk mixture and mash everything to puree. Season to taste with salt and nutmeg.
Lightly brown 4 tablespoons of butter. Remove from the heat and briefly warm the rest of the crab meat in it. Arrange fish with mashed potatoes and crab butter. Sprinkle with remaining parsley.