Cook macaroni according to package directions; drain. Return macaroni to saucepan. If desired, remove any darker outer layer from smoked cheese with a vegetable peeler. Shred cheese (you should have about 3/4 cup); set aside.
For sauce, in a medium saucepan combine broth and onion. Bring to boiling; reduce heat to medium. Cook, covered, about 5 minutes or until onion is tender. In a screw-top jar combine half-and-half, flour, mustard, and black pepper; cover and shake well. Add to onion mixture. Cook and stir just until bubbly. Remove from heat. Add smoked cheese, stirring until most of the cheese is melted. Pour the sauce over cooked macaroni; toss to combine. Pour into a 1 1/2-quart casserole.
Bake, covered, in a 350 degree F oven for 10 minutes. Uncover and bake about 10 minutes more or until bubbly. Let stand for 5 minutes. Top with chopped apple and Parmesan cheese. Makes 4 servings.