HEAT 2 Tbsp. dressing in large skillet on medium heat. Add chicken; cook and stir 5 min. or until cooked through.

STIR in remaining dressing, water, broth, soy sauce and peanut butter. Bring to boil. Add spaghetti; cover. Simmer 5 min.

ADD vegetables; mix lightly. Simmer, covered, 4 to 6 min. or until spaghetti is tender.