Rub microwave-safe plate with butter. Set aside. Clean and trim mushrooms. Remove stalks and chop finely. Combine stalks with chopped olives, half and half, brandy, chives and tarragon. Add salt and pepper to taste. Fill mushroom caps with mixture. Arrange caps, filled side up, on buttered plate. Sprinkle with chopped parsley, then cover with plastic wrap. Microwave 2 to 3 minutes, or until mushrooms are tender and filling is heated through. Serve at once.