In a heavy round ovenproof baking dish spread enough rock salt to make a 1-inch layer. Preheat oven to 375 degrees F.
In a small bowl combine bacon, celery, chervil, green onions, parsley and spinach. Season with salt and pepper and sprinkle with lemon juice and optional Pernod. In another bowl combine bread crumbs with oil and Creole seasoning; season with salt and pepper.
Carefully open oysters and discard top shell. Drain liquid, loosen oyster and remove any grit or sand. Push oyster shells firmly into the rock salt. Top with greens mixture, then with bread crumb mixture. Bake 10 to 15 minutes until bread crumbs are lightly browned. Serve immediately, directly from baking dish.
Yield: 12 appetizers