Brown the beef in a skillet over medium heat until browned. Drain excess grease.
Add cooked beef to the slow cooker along with onion, bell pepper, garlic, tomato paste, Worcestershire sauce, and all seasonings. Stir to combine.
Pour in beef broth and milk. Stir well. Cover and cook on LOW for 6–7 hours or HIGH for 3–4 hours.
About 20 minutes before serving, stir in uncooked pasta, heavy cream, and cream cheese.
Cover and cook until pasta is tender, about 15–20 minutes.
Stir in shredded cheddar until melted and creamy. Season with salt and pepper to taste. Garnish with parsley if desired.
