Cook macaroni according to package directions. Meanwhile, in a large saucepan, melt butter. Stir in the flour, parsley, mustard and pepper until blended. Gradually stir in milk. Bring to a boil; cook and stir for 2 minutes or until thickened. Stir in cheese until melted.
Drain macaroni; add to cheese sauce. Stir in the ham, asparagus and mushrooms. Transfer to a greased 2-1/2-qt. baking dish. Sprinkle with bread crumbs. Bake, uncovered, at 350° for 25-30 minutes or until bubbly.