In a pot, heat the broth over medium heat until well heated, keeping it at a simmer. Do not bring to a boil. Beat the egg yolks and cream together until they are thick. Mix in wine, cinnamon, and salt. Temper egg yolk and broth. Pour mixture into the broth, mixing continually until the soup is well mixed and creamy. Do not let it boil. Serve with croutons sprinkled over soup.