Clean, wash and cut the leek into rings. Peel and slice the onions. Heat 2 tablespoons of oil in a frying pan. Fry the leek and onions for about 4 minutes, turning them over. Season with salt, pepper and nutmeg, remove from the pan and set aside
Bring the stock and cream to the boil in a saucepan. Stir in onion soup powder, simmer soup while stirring for about 4 minutes. Add sauce thickener and simmer for about 1 minute more. Season to taste with salt and pepper, put aside. Grate cheese
Heat 2 tablespoons of oil in a large frying pan and fry the slices of pork on both sides for 3-4 minutes. Toast the bread and place flat in a greased casserole dish. Cover toast slices with cured pork loin. Spread leek and onion rings on top. Pour sauce over it and sprinkle with cheese. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 10-15 minutes