COOK pasta as directed on package, omitting salt.
MEANWHILE, cook sausage in large nonstick skillet on medium-high heat 10 min. or until sausage is done, stirring occasionally. Drain sausage; return to skillet. Add tomatoes, onions and dressing; mix well. Cook 5 min. or until onions are crisp-tender, stirring occasionally.
DRAIN pasta. Toss with sausage mixture and 1/2 cup cheese; sprinkle with remaining cheese.
serving size = 1-3/4 cups (425 mL)