(Optional) In a skillet over medium heat, brown the ground beef and onion until no longer pink. Drain any excess grease.
Transfer the beef mixture to your slow cooker. Add garlic, cream of mushroom soup, beef broth, Worcestershire sauce, paprika, salt, and pepper. Stir to combine.
Cover and cook on low for 6–7 hours or high for 3–4 hours.
About 20 minutes before serving, cook the egg noodles separately in salted water until tender. Drain and set aside.
Turn off the slow cooker. Stir in sour cream until smooth and creamy.
Add the noodles and gently mix until fully coated.
Serve hot, garnished with fresh parsley if desired.