The mussels can be scrubbed and beards removed several hours ahead of time.
makes about 20
1 tablespoon oil
1 onion, finely chopped
6 thin slices prosciutto, chopped
4 cloves garlic, crushed
3 pound black mussels
1/2 cup Parmesan, grated
1/2 cup Cheddar, grated
1. Heat the oil in a small skillet and add the onion, prosciutto, and garlic. Cook over medium heat for 5 - 8 minutes, until the prosciutto is crispy and the onion softened, then set aside.
2. Scrub the mussels with a stiff brush and pull out the hairy beards. Discard any broken mussels, or open ones that don't close when tapped on the bench. Add to a large pan of boiling water and cook for 5 minutes. Stir occasionally and discard any mussels that don't open. Remove the mussels from their shells, keeping half of each shell. Place 2 mussels on each half-shell and top each with a little of the prosciutto mixture.
3. Combine the Parmesan and Cheddar and sprinkle over the prosciutto. Cook under a preheated grill until the cheese has melted and the mussels are warmed through.