Drain the potatoes and transfer to a large bowl. Beat with a mixer at medium speed until potatoes are mashed and smooth. Beat in the melted butter, salt, and pepper. Gradually beat in the hot milk until potatoes are light and fluffy. Beat the egg whites until stiff but not dry, then gently fold the whites into the potatoes. Preheat the broiler. Reheat the stew, if refrigerated. Taste and adjust the seasoning. Transfer the stew to a broilerproof serving dish or shallow casserole. Spoon the hot potatoes into a pastry bag fitted with a star tip and pipe the potatoes on top of the stew. Drizzle with the melted butter. Broil 6 inches from the heat until lightly browned, and serve immediately.
HAM AND CHEESE PIE Makes 6 to 8 servings This is a great pie to make when you have leftover cooked ham after a holiday meal. My husband takes chilled wedges of it in his lunchbag, and it's just delicious served with a freshly grated horseradish sauce or creme fraiche flavored with curry. 1/2 recipe Lemon Pastry (page 94) 1 tablespoon coarse-grain mustard 1 tablespoon butter 1 cup chopped fresh mushrooms 1 cup chopped scallions (green onions) 70