Cook macaroni according to package directions; drain and set aside.
In a large saucepan, melt butter over medium heat. Stir in the flour, salt, mustard, pepper and Worcestershire sauce until smooth; gradually add milk and cream. Bring to a boil over medium heat; cook and stir for 1 minute or until thickened. Stir in cheeses until melted. Stir macaroni into cheese mixture.
Transfer to a greased 2-qt. baking dish. Sprinkle with bread crumbs, bacon, Parmesan cheese and onions. Bake, uncovered, at 350° for 20-25 minutes or until bubbly and golden brown.