To make stew with canned oysters, heat milk until it is scalded, and cook onion, parsley, salt, pepper, cayenne pepper and oysters in a separate pan. Add flour to the oyster mixture to thicken it, and stir the oysters into the scalded milk to complete the stew.
In a saucepan, begin heating 3 cups of milk until the milk is scalded. In a separate pan, melt 2 tablespoons of butter over low heat, and cook 1 grated onion and 2 tablespoons of fresh parsley until the onion is soft. Add 2 tablespoons of Worchester sauce and a pinch each of cayenne pepper, salt and pepper to the onion mixture. Drain two 8-ounce cans of oysters, reserving the liquid. Add the liquid to the onion mixture, and bring the liquid to a boil.
After the liquid is boiling, whisk 1/3 cup of flour into the onion mixture. Stir constantly until the mixture is thickened, and add the oysters. Cook the oysters in the sauce for approximately five minutes, or until the edges of the oysters begin to curl. Pour the oyster and onion mixture to the scalded mix. Stir well to incorporate the ingredients, and serve the stew with hot sauce and crackers or bread.