1Spray 12-inch nonstick skillet with cooking spray. If beef roast comes in netting or is tied, do not remove. Sprinkle beef with Italian seasoning, salt and garlic pepper. Cook beef in skillet over medium-high heat 6 to 8 minutes, turning occasionally, until brown on all sides.
2Spray 5- to 6-quart slow cooker with cooking spray. Place onion in cooker. Top with beef. Pour dressing over beef and onion.
3Cover and cook on Low heat setting 8 to 9 hours.
4Place beef on cutting board; remove netting or strings. Cut or shred beef into small pieces. Return beef to cooker. To serve, spread cut sides of buns with tomato spread; sprinkle with basil. Layer beef, onion mixture and cheese in buns.