In a large skillet over medium heat, cook and crumble ground beef. Drain any excess fat.
Add onion, bell pepper, and garlic. Cook 3-5 minutes, or until the vegetables are slightly tender. Season with seasoning salt or salt and black pepper as desired.,
To a Crockpot, whisk together cream of mushroom soup, beef broth, crushed tomatoes, tomato sauce, Italian seasoning, crushed red pepper flakes, and seasoning salt or salt and black pepper.
Add the cooked beef mixture to a slow cooker, and stir until combined.
Cover and cook on low 6-7 hours or on high 2-3 hours.
In the last 15 minutes of cooking, stir in uncooked elbow macaroni. Cover and turn the heat to high.
Stir in shredded cheddar cheese. Cover again until cook until the cheese is melted and pasta fully cooked, about 2-3 minutes.
Give the mixture one last stir, taste, and adjust the seasoning if necessary. Garnish as desired, and serve hot.