Beat the butter with salt, pepper, nutmeg and eggs until frothy. Gradually stir in the semolina until a well malleable dough is formed. Put the dough in the refrigerator for an hour.
In the meantime, bring 2 liters of beef broth to the boil. Season the broth with cayenne pepper and chilli flakes.
Prick the dough with 2 teaspoons and let them steep in the simmering broth for about 20-25 minutes until they are cooked through. Finely chop the parsley and add to the soup.