In 10-inch nonstick skillet, cook ground beef and onion over medium-high heat, stirring frequently, until beef is thoroughly cooked; drain.
Spray 3 1/2- to 4-quart slow cooker with cooking spray. Place beef mixture in slow cooker; top with tomatoes.
Cover; cook on High heat setting 4 hours (or on Low heat setting 8 hours).
About 15 minutes before serving, cook and drain pasta as directed on package. Divide pasta among 4 serving bowls.
When sauce is done, stir in salt. Spoon meat sauce over pasta. Top individual servings with cheese, basil and pepper.