In a skillet, sauté oil and onion over medium heat until softened. Add garlic and cook for 1 minute. Stir in the tomato sauce, basil, salt, oregano, pepper and cooked chicken. Bring to a boil. Reduce heat; simmer, uncovered, for 20 minutes. Meanwhile, cook pasta until al dente according to package directions; drain. To serve, serve sauce over pasta and sprinkle with Parmesan, if desired. |