1Spray inside of 3- to 4-quart slow cooker with cooking spray. If beef is tied, remove strings or netting. Place beef in cooker. Sprinkle with brown sugar. Pour dressing over beef.
2Cover and cook on Low heat setting 10 to 12 hours.
3Remove beef from cooker; place on cutting board. Shred beef, using 2 forks. Return beef to cooker; add Italian seasoning and mix well. Using slotted spoon to remove beef from cooker, fill each bun with about 1/3 cup beef. Serve with remaining juices.