Sort the spinach, wash, clean and drain in a sieve. Peel and halve the onion and cut into fine cubes. Peel garlic and chop finely. Heat 1 tablespoon of oil in a saucepan and sauté the onion and garlic.
Add the spinach and let it collapse. Season to taste with salt, pepper and nutmeg.
Dab meat dry. Heat 2 tablespoons of oil in a pan and fry the Kassler in it until golden brown on each side. Pour cream into the spinach and crumble the gorgonzola into it. Let the sauce simmer gently until the cheese has melted, season with salt and pepper.
Roughly grate the gouda. Place the meat in an ovenproof dish (25 x 40 cm), spread the spinach sauce on top, sprinkle with Gouda and bake in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: see
manufacturer) bake for about 20 minutes. Take out of the oven and arrange.