Rub the butter over the bottom of a shallow flameproof casserole or skillet. Trim off the bottoms and any damaged outer leaves of the endive and cut the heads into diagonal slices about 3 cm thick. Put them in the pan with salt and pepper to taste, lemon juice and water. Press a piece of buttered foil on top of the endive and cover with a lid. Cook over low heat for 7-8 minutes or until the endive is tender. Shake the pan occasionally. Sprinkle with the chopped parsley and serve.