Wash the spinach, shake dry. Peel and finely dice the shallots. Heat 1 tbsp. butter in a pan and sauté the shallots briefly until translucent. Add the spinach and cook covered for 2-3 minutes. Drain well, stir in double cream and season to taste with salt and nutmeg. Spread the mixture over 6 greased soufflé cups (approx. 200 ml each)
Pluck the fish with a fork, removing any bones. Melt 50 g butter in a pot, stir in flour and sweat briefly. Add 250 ml milk while stirring, bring to the boil and simmer for about 3 minutes. Add the fish and simmer for another 2 minutes
Separate eggs, mix egg yolks and remaining milk, add to the sauce while stirring and season to taste with lemon juice, salt and pepper. Beat the egg white in 2 portions until stiff and fold into the fish mixture. Divide into the soufflé cups and bake in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: see manufacturer) for approx. 30 minutes until the soufflés have risen and are golden brown in colour. Serve immediately