Using a food processor, chop the spinach, breadcrumbs, green onions, bacon and parsley. Add the remaining ingredients and process until finely chopped but not pureed, about 10 seconds. Layer the oysters in their half shells on a pan with rock salt. Spoon some of the spinach mixture one each oyster. Bake 10 minutes until cooked through, then broil until browned on top. Serve hot.