Line a mixing bowl with a sieve and pour in the oysters. Reserve the oyster liquor and add enough water or bottled clam juice to make 1cup. Pat the oysters with paper towels to remove excess moisture.
Heat the butter in a saucepan and add the flour, stirring with a wire whisk. When blended and smooth, add the oyster liquor mixture, stirring rapidly with the whisk. When blended and smooth, add the cream and stir.
Add salt, pepper, Worcestershire, nutmeg, and cayenne. Add the oysters and cook briefly over gentle heat until the edges curl.
Serve over hot buttered toast triangles. Sprinkle each serving with an equal amount of chopped parsley.