COOK spaghetti in large saucepan as directed on package, omitting salt and adding broccoli to the boiling water for the last 5 min.; drain.
MELT butter in same saucepan on medium heat. Add chicken and garlic; cook and stir 1 to 2 min. or until chicken is heated through and garlic is tender.
ADD spaghetti mixture; mix lightly. Sprinkle with cheese; toss to coat.