Cook the rice in the clam juice in a pan until very soft. Add the butter. Force the mixture through a fine sieve, or whirl in the blender until smooth. Finely chop 12 of the oysters (or whirl in the blender or food processor until finely chopped; if you use the blender it will be necessary to add a little of the oyster liquor). Combine chopped oysters and rice mixture in a pan. Season to taste with salt and pepper and add the Tabasco. Stir in the heavy cream. Heat just to the boiling point. Add the 6 whole oysters and heat until they just curl at the edges. Add the cognac and cook 2 minutes. Ladle the soup into heated cups, putting a whole oyster in each cup. Garnish with chopped parsley and serve with Melba toast.

VARIATION:

Clam Bisque: Use fresh or canned clams instead of oysters.