Preheat the grill to a medium to high heat. Arrange the oysters in the bottom half of the shells and place on a baking sheet.
Melt the butter in a small pan, add the shallot and cook until soft. Stir in the chervil, cream and seasoning to taste.
Place a spoonful of the sauce on top of each oyster and sprinkle with the cheese and breadcrumbs. Grill until golden brown. Serve with a watercress salad and crusty bread.