Clean and debeard the mussels; place in a buttered casserole dish. Season with salt and pepper.

Arrange on the top the thinly sliced onion and slices of bacon that have been cut in half. Add the sherry.

Cover and bake in a preheated 350° oven for 15-20 minutes.

Remove the lid and sprinkle with grated cheese. Return to the oven and allow the cheese to melt.

Serve with your favourite crusty bread.