Cream the butter, add lemon juice drop by drop, salt, pepper, and parsley. Cut bread in circular piece three-eighths inch thick, then toast. Put one-half of the sauce on the under side of toast; put toast on a small baking dish, pile mushroom caps cleaned and pealed in conical shape on toast, and pour over cream. Cover with glass and bake about twenty-five minutes, adding more cream if necessary. Just before serving add one teaspoon Sherry wine.