Cook the macaroni in plenty of salted water until tender, 8 to 10 minutes. Drain and cool under cold running water. Prepare the White Sauce, and while still hot, toss all but two tablespoons of it with the macaroni, mustard, cayenne, Cheddar, salt and pepper. Turn into a large buttered casserole and top with the munster cheese.
Bake in a preheated 375 degree oven for 15 minutes, or until the top is crusty and brown. Spread the remaining 2 tablespoons White Sauce over the top. Cover with a layer of parmesan cheese mixed with the breadcrumbs. Dab with the butter. Return to the oven for 10 more minutes. Place under high broiler for 1 minute to brown the top and serve immediately.
Makes 4 servings.