Peel and chop the potatoes, cover and cook in 1/4 litre of boiling salted water for 20 minutes. In the meantime wash apples, cut out the core. Peel onions, dice finely and sauté in 10 grams of fat.
Wash the marjoram, chop finely and mix into the onions. Season to taste with salt and some pepper and fill into the apples. Put them into a small ovenproof bowl spread with fat and roast them in the preheated oven (electric cooker: 200 °C/ gas: level 3) for 20 minutes.
Clean, wash, halve or quarter the mushrooms. Heat 20 grams of fat in a pan. Fry the mushrooms in it while turning. Deglaze with stock and cream and simmer for five minutes. Thicken with sauce thickener and season to taste with salt and pepper, keep warm for a short time.
Drain and mash the potatoes. Heat the milk, melt the remaining fat in it and stir into the potato mixture. Season to taste with salt and nutmeg. Drain the peas on a sieve and fold them into the hot mashed potatoes.
Sprinkle puree with nutmeg and arrange on portion plates with baked apples and mushroom sauce. Garnish as desired with a bouquet of herbs.