In a large skillet over medium heat, cook the ground beef and diced onion until the beef is browned and the onion is soft, about 5-7 minutes. Drain excess fat.
Add the minced garlic to the skillet and cook for 1 minute until fragrant. Remove from heat.
In the crock pot, combine the cooked beef mixture, diced tomatoes with their juice, cream of mushroom soup, cream of celery soup, beef broth, Italian seasoning, salt, and black pepper. Stir well to combine.
Add the uncooked egg noodles to the crock pot and stir to distribute evenly.
Cover and cook on low for 4 hours, or until the noodles are tender and the casserole is bubbly.
About 10 minutes before serving, sprinkle the shredded cheddar cheese evenly over the top of the casserole. Cover and cook until the cheese is melted, about 10 minutes.
Stir gently before serving to mix the melted cheese throughout the casserole.