For the egg whisk eggs and milk well and season with salt and nutmeg. Pour into a greased rectangular flat casserole dish (approx. 600 ml capacity). Cover with aluminium foil and place on the fat pan of the oven. Pour on hot water so that the dish is in water to approx. 2⁄3. Leave in the hot oven (electric cooker: 150 °C/circulating air: 125 °C/gas: see manufacturer) for approx. 45 minutes. Lift the mould out of the water and remove the foil. Let the egg pit cool down.
Wash meat for the broth. Halve onions with skin and roast them in a large pot without fat for about 5 minutes on the cut surface until dark brown. Pour on approx. 4 l water. Add meat and bring to the boil. Skim off any foam that develops.
In the meantime, peel or clean the soup greens, wash and roughly dice them. Add soup vegetables and spices to the meat and simmer for about 2 hours.
Peel, wash and thinly slice the carrots. Wash and peel asparagus, cut off woody ends. Cut asparagus into pieces. Clean, wash and chop the mangetouts.
Remove the meat from the broth. Set aside half the meat for the boiled beef salad. Finely dice the rest of the meat for the soup. Pour stock through a sieve into a second pot and bring to the boil.
Press the sausage meat directly from the skin as dumplings into the hot broth. Add asparagus and carrots and cook for about 5 minutes. Add mangetouts and meat and cook for another 2 minutes. Dice the eggs. Season soup with salt and pepper. Heat the egg whites in the soup. Serve the soup with parmesan swans.
Quickly knead flour, salt, cold butter in pieces, eggs, grated Parmesan cheese and sour cream with your hands to a smooth dough. Wrap in cling film and chill for about 1 hour. Roll out the dough in portions on some flour to a thickness of approx. 3 mm. Cut out approx. 30 circles (each approx. 8 cm Ø), kneading the dough again and again.
Fold circles into semicircles. Cut semicircles on one side once deep and twice shorter. Bend the first incision upwards to form a swan head. Distribute on baking trays lined with baking paper. Whisk 1 egg, brush swans with it. Put linseed as eyes on it. Bake one after the other in a preheated oven (electric oven: 200 °C/circulating air: 175 °C/gas: see manufacturer) for about 12 minutes. Remove and let cool off.