Heat the oil in a pan and fry the potato pancakes in it in portions on both sides for 2-3 minutes at medium heat. In the meantime, clean and wash the leek and cut it into rings. Clean the mushrooms, wash if necessary and cut in half. Take the potato pancakes out of the pan and keep them warm. Add leek and mushrooms to the frying fat and fry.
Season with salt and pepper. Take out some leek and put aside. Deglaze the rest with stock and cream and bring to the boil. Bind with sauce thickener and season again. Grate cheese finely. Put 3 potato pancakes on a baking tray covered with baking paper and spread about half of the mushroom ragout on top. Sprinkle with some cheese. Cover each with another potato pancake and spread the rest of the ragout on top. Sprinkle with cheese and put the remaining 3 potato pancakes on top as a lid.
Put 3 potato pancakes on a baking tray covered with baking paper and spread about half of the mushroom ragout on top. Sprinkle with some cheese. Cover each with another potato pancake and spread the rest of the ragout on top. Sprinkle with cheese and put the remaining 3 potato pancakes on top as a lid. Sprinkle with cheese and leek and bake in a preheated oven (electric: 200 °C/ gas: level 3) for 8-10 minutes. Arrange on plates and garnish as desired with chilli peppers and parsley and serve