Prepare and cook as in Boiled Jerusalem Artichokes (opposite). Drain well and shake the pan over a low heat to dry the artichokes slightly. Mash with a fork or potato-masher or rub through a nylon sieve. Heat the butter or margarine in the pan and beat in the purée. Stir over heat until thoroughly hot. Season well. Serve in a hot vegetable dish and sprinkle with chopped parsley.