COOK pasta as directed on package, omitting salt.
MEANWHILE, brown meat with onions and garlic in large skillet. Add zucchini, corn and chili powder; cook 7 min. or until vegetables are tender, stirring occasionally. Stir in tomatoes and salsa; cook 3 min. or until heated through, stirring occasionally.
DRAIN pasta. Add to meat mixture; mix lightly. Stir in 1/2 cup cheese. Serve topped with remaining cheese.