HEAT oven to 375ºF. Cook pasta in large saucepan as directed on package, adding broccoli for the last 3 min.

MEANWHILE, heat large nonstick skillet on medium-high heat. Add chicken; cook 3 min. or until no longer pink, stirring frequently. Stir in broth; simmer 3 min. or until chicken is done. Add Neufchatel; cook and stir on low heat 1 min. or until cream cheese is melted. Stir in 1/2 cup mozzarella.

DRAIN pasta and broccoli. Add to chicken mixture; mix lightly. Spoon into 8-inch sq. baking dish; cover.

BAKE 15 min. or until heated through. Sprinkle with remaining cheeses. Bake, uncovered, 3 min. or until melted. Let stand 5 min.