Creamy Ham & Macaroni Bake

7 Ounces elbow macaroni, uncooked
2 Tablespoons butter
3 Tablespoons flour
1 Teaspoon salt, if desired
1 Teaspoon parsley flakes
3/4 Teaspoon dry mustard
3 Tablespoons dry breadcrumbs
1 (6 ounce) Can mushrooms
1/4 Teaspoon pepper
2 Cups milk
2 1/2 Cups shredded American cheese
2 Cups diced ham
1 (10 ounce) Package frozen asparagus cuts thawed, drained
OR
1 (10 1/2 ounce) Can asparagus, drained

Prepare macaroni as package directs; Drain and set aside. Heat oven to 350F. In large saucepan, melt margarine. Stir in flour, salt, parsley flakes, dry mustard and pepper. Blend in milk; Cook stirring continually until thick and bubbly. Add cheese; Stir until melted. Add cooked macaroni, ham, asparagus and mushrooms; Mix well. Pour into buttered 2-quart casserole. Sprinkle with breadcrumbs. Bake at 350F for 30 minutes or until bubbly. Refrigerate leftovers.