Cook the lasagne sheets in boiling salted water for 5-7 minutes until al dente
Peel and finely dice the garlic and onion. Heat 1 tablespoon of oil and 2 tablespoons of water in a saucepan. Steam onion, garlic and spinach for about 7 minutes. Wash the fish, dab dry, dice and season with salt and pepper. Heat 1 tablespoon of oil in a coated pan.
Fry the fish for approx. 5 minutes, turning carefully. Remove the lasagne sheets and rinse with cold water. Season spinach with salt, pepper, sugar and nutmeg and let it drain on a sieve. Melt the fat. Sweat flour in it. Add milk, orange juice and horseradish, stirring constantly, and continue to simmer for 2 minutes. Season to taste with salt and pepper. Cover one half of the lasagne sheets with spinach and salmon. Drizzle with part of the sauce. Fold the lasagne sheets together and layer them diagonally in an ovenproof dish, sprinkling each packet with the remaining sauce.
Season to taste with salt and pepper. Cover one half of the lasagne sheets with spinach and salmon. Drizzle with part of the sauce. Fold the lasagne sheets together and layer them diagonally in an ovenproof dish, sprinkling each packet with the remaining sauce. Cut the mozzarella into cubes and place on the parcels. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for about 20 minutes. Remove the tin, arrange the parcels on preheated plates and garnish with cress