In 3-quart saucepan combine leek or onion, potato, water, bouillon granules, and white pepper. Bring to boiling. Reduce heat; cover and simmer for 7 minutes or until potatoes are done. Do not drain.
Stir in evaporated skim milk. Cook over medium heat for 5 minutes. Add undrained oysters. Cook about 5 minutes more or until edges of oysters curl, stirring frequently. Stir in parsley. Stir in butter-flavored sprinkles, if desired. Makes 6 servings.