HEAT oven to 350ºF.
COOK and stir vegetables in large nonstick skillet sprayed with cooking spray on medium heat 3 min. or until crisp-tender. Add cream cheese, milk and garlic salt; cook on low heat 3 to 5 min. or until cream cheese is melted, stirring frequently.
ADD pasta, chicken and 1/4 cup Parmesan; spoon into 2-1/2-qt. baking dish.
BAKE 20 to 25 min. or until heated through. Sprinkle with remaining Parmesan.