Peel and wash the potatoes and cook them in boiling salted water for about 20 minutes. Peel and finely dice the onion. Knead the mince, egg and onion. Season with pepper and marjoram. Form 8 meatballs from the minced meat dough.
Heat 2 tablespoons of oil in a frying pan. Fry the meatballs for about 15 minutes at medium heat. Peel and halve the shallots. Wash and quarter apples, cut out the core. Cut apple quarters into slices.
Heat 1 tablespoon of oil in a frying pan. Sauté the shallots in it. Add apple slices to the shallots and fry briefly. Season with marjoram and pepper. Deglaze with stock, bring to the boil and cook for 3 minutes.
Drain and mash the potatoes. Stir in milk and butter. Season to taste with salt and nutmeg. Arrange mashed potatoes, meatballs and apple-shallots vegetables on plates. Serve sprinkled with marjoram.