Brown the Beef: In a skillet over medium heat, cook the ground beef with the diced onion until the beef is browned and fully cooked. Drain any excess grease. Add the minced garlic, Italian seasoning, salt, and black pepper, cooking for 1-2 minutes until fragrant.

Add Ingredients to Slow Cooker: Transfer the cooked beef mixture to the slow cooker. Stir in the diced tomatoes, beef broth, and heavy cream.

Cook the Base: Cover and cook on low for 6-8 hours or on high for 3-4 hours.

Add Pasta: During the last 30 minutes of cooking, add the uncooked pasta to the slow cooker. Stir to combine, ensuring the pasta is submerged in the liquid. Cover and cook until the pasta is tender.

Stir in Cheese: Once the pasta is cooked, stir in the shredded Parmesan cheese until melted and creamy.

Serve: Garnish with fresh parsley if desired and serve hot.