COOK onions in dressing in large skillet on medium heat. Increase heat to medium-high. Add meat; cook, stirring frequently, until browned. Stir in tomato sauce and tomatoes. Bring to boil. Reduce heat to medium-low; simmer 15 min. Remove from heat. Stir in Neufchatel cheese until well blended.

MEANWHILE, cook pasta as directed on package.

SPOON sauce over pasta. Sprinkle with Parmesan cheese.