Stuffed mussels make a great appetizer and even work as a nice Hors d’Oeuvres. They are rather simple to make, composed of two fillings. The cooked mussels are combined with chopped Serrano ham, garlic and tomatoes and spooned into the shells. They are topped with the second filling, a Mussel-White Sauce (bechamel) made with the reserved cooking liquid from the mussels. The mussels can be made a day ahead of time and finished at the last minute in a frying pan.