Peel and wash the parsley root and cut into thin slices. Bring the stock to the boil, add the parsley root and cook for 10 minutes. Then drain. Collect the broth. In the meantime wash parsley and pluck leaves.
Put some leaves aside for garnishing. Add remaining leaves to the stock and puree. Melt the fat in a saucepan. Sweat flour in it. Add cream and parsley broth while stirring constantly, bring to the boil.
Put in root discs. Season to taste with salt, pepper and nutmeg. Heat the oil in a frying pan. Beat in the egg. Let the egg yolk melt a little. Salt a little bit. Fry briefly on both sides, then cut into strips and add to the soup.
Serve the soup sprinkled with retained parsley leaves.