Cook macaroni in boiling salted water till just tender, 8 to 10 minutes; drain. In large saucepan melt the quarter cup butter; blend in flour, brown sugar, mustard, salt and pepper. Add milk all at once; cook and stir until thickened and bubbly. Stir in cooked macaroni, ham and apple slices. Turn mixture into a 2 litre casserole. Combine bread crumbs and the 2-tb melted butter; sprinkle over casserole. Bake, uncovered, at 180ºC or about 35 minutes.