Wash the potatoes thoroughly and cook in boiling water for about 20 minutes. Peel and finely dice the onion. Cut the mead into slices. Clean and clean the mushrooms and cut into thick slices.
Heat 2 tablespoons of oil in a large frying pan. Sauté the mushrooms for 3-4 minutes while turning them. Add slices of sausage and diced onion. Fry briefly, then remove. Add 200 g cream and stock and simmer for about 4 minutes.
Wash the marjoram, shake dry, put a stalk aside for garnishing. Pluck the leaves from the remaining stems and chop them coarsely. Add mushroom sausage mix and chopped marjoram and season to taste with salt, pepper and paprika.
Drain the potatoes, rinse and peel them. Cut the potatoes into slices and place them in an ovenproof dish, raising the rim. Fill the sausage-mushroom cream in the middle. Cover with bacon slices. Grate cheese.
Heat 5 tablespoons of cream, remove from heat and stir in the grated cheese briefly (should not dissolve completely). Sprinkle the cheese cream over the casserole and bake in a preheated oven (electric range: 175 °C/ convection oven: 150 °C/ gas: level 2) for approx. 30 minutes.
Remove from the oven and garnish with marjoram.