Put the fish in a baking dish and make shallow diagonal 3 inch long cuts on each side of the fish. Season each side of the fish with 1/2 teaspoon of salt and 1/2 t of the Creole seasoning. Let the seasoned fish rest in the fridge while you make the sauce.
Preheat the oven to 300 degrees F.
Melt the butter in a medium stockpot over med-high heat. Add your onions, bell peppers, celery, the remaining 2 t of salt, cayenne, thyme and the bay leaves. Cook, stirring frequently, about 10 minutes - until the onions are soft and golden. Stir in the green onions and garlic and cook for about 1 minute. Stir in the flour and cook, stirring, for about 2 minutes (don't brown the flour).
Add the tomatoes, chicken stock, Worcestershire sauce and the pepper sauce. Cook this mixture over medium heat for about 10 minutes. Add the parsley and then remove the sauce from the heat and let cool for about 15 minutes.
Pour the sauce over the red snapper and bake it for about 1 hour, until the flesh if firm and cooked through (if you are using smaller fish filets, you will have to adjust the time down).
Loosen the head from the fish and remove. Run a spoon down the back of the fish to find the spine. Gently loosen the flesh from the spine and the bones, slipping a wide spatula under the flesh, lift the flesh away from the gones and lay the filet of fish on a serving plate. Gently pull the fish skeleton away from the bottom filet and discard. Lift the bottom filet from the roasting pan and put on the serving plate. Remove and discard the bay leaves and pour the sauce into a bowl for serving.
Serve the fish with the sauce spooned over the top!