Preheat oven to 350°. In a 6-qt. stockpot, cook macaroni according to package directions for al dente; drain and return to pot., Meanwhile, in a medium saucepan, melt butter over medium heat. Stir in flour, salt and pepper until smooth; gradually whisk in milk. Bring to a boil, stirring constantly; cook and stir until thickened, 1-2 minutes. Stir in cheeses until blended. Stir in dressing., Add chicken and sauce to macaroni, tossing to combine. Transfer to a greased 13x9-in. baking dish., Toss bread crumbs with melted butter; sprinkle over macaroni. Top with bacon. Bake, uncovered, 30-35 minutes or until topping is golden brown. Sprinkle with parsley. Freeze option: Prepare recipe as directed, increasing milk to 1-1/3 cups. Cool unbaked casserole; cover and freeze. To use, partially thaw in refrigerator overnight. Remove from refrigerator 30 minutes before baking. Preheat oven to 350°. Cover casserole with foil; bake 30 minutes. Uncover; continue baking as directed or until heated through and a thermometer inserted in center reads 165°.