Wash spinach in five or six waters, then chop it very fine and mix it with butter, salt it and warm it up. Then let it get cold, pass through a hair sieve, and add eggs, Parmesan, and very little nutmeg. Add this to some boiling stock in a copper saucepan, put on the lid, and on the top put some hot coals so that the eggs may curdle and help to thicken the soup. Serve with fried croutons.