Cook ravioli as directed on package; drain.
Meanwhile, in 8-inch nonstick skillet, cover and cook onion over medium heat 3 to 5 minutes, stirring occasionally, until crisp-tender. Uncover; stir in tomatoes and olives. Cook uncovered 3 to 5 minutes, stirring frequently, until thoroughly heated.
Gently stir in cooked ravioli. Cook 3 to 5 minutes, stirring occasionally, until sauce is desired consistency. Sprinkle individual servings with cheese and basil.