Cook pasta according to package directions; drain. Meanwhile, season chicken with garlic powder, salt and pepper, if desired.
Cook chicken, sweet pepper and onion in oil in large skillet over medium-high heat 5 minutes, or until chicken is no longer pink. Add undrained tomatoes; simmer, uncovered, 5 minutes or until slightly thickened. Add olives, if desired.
Toss with hot pasta. Serve with shredded Parmesan cheese, if desired.