Combine fire-roasted tomatoes, tomato sauce, beef broth, tomato paste, Italian seasoning, Worcestershire sauce, and garlic in a 4-quart slow cooker. Stir well.
Heat olive oil in a large skillet over medium-high heat. Add onion and cook 2-3 minutes until softened.
Add ground beef, salt, and pepper. Cook, breaking it up, until browned and no pink remains, about 6-8 minutes. Drain excess fat.
Transfer beef and onion to the slow cooker. Stir to combine with the sauce.
Cover and cook on LOW for 6-8 hours (or HIGH for 2-4 hours).
About 45 minutes before serving, stir in elbow macaroni. Cover and cook until al dente, checking at 40 minutes.
If too thick, add a splash of broth or water. Taste and adjust salt and pepper.
Ladle into bowls and top with shredded cheddar cheese if desired. Serve hot.