MELT butter in large nonstick skillet on medium heat. Add cracker crumbs, 2 Tbsp. parsley and garlic; cook 2 min. or until crumbs are golden brown, stirring frequently. Place in small bowl; stir in Parmesan.
COOK macaroni as directed in package. Meanwhile, cook chicken, in batches, in same skillet 2 to 3 min. or until no longer pink, stirring frequently. Return all the chicken to skillet. Add tomato sauce and remaining parsley; cover. Simmer on medium-low heat 5 min. Add Singles; cook and stir 1 to 2 min. or until melted.
DRAIN macaroni. Add to chicken mixture in skillet; stir. Cook and stir 1 min. or until heated through. Top with mozzarella; cover. Remove from heat; let stand 2 min. or until melted. Top with crumb topping.