6 cups hot rich meat broth (all chicken, all beef or combination of these; freshly made or canned)
2 ounces (1/8 of a 1-pound package) vermicelli
1/4 pound (1/2 cup) soft sweet (unsalted) butter
3/4 cup freshly grated parmesan cheese
4 egg yolks
1 cup heavy cream
Bring broth to boiling over direct heat (on a range top or over a denatured alcohol flame). Add vermicelli (broken, if desired) and cook uncovered, for 5-8 minutes or until noodles are tender to bite.
In a bowl blend the sweet butter with cheese and egg yolks, then gradually beat in the cream (If you cook at the table, prepare this mixture in the kitchen.) Spoon a small amount of the hot broth into the cream mixture stirring constantly, then pour this mixture back into the hot broth, stirring constantly.
Extinguish heat if chafing dish, or remove from heat. Ladle into bowls.