Place the beef strips, sliced mushrooms, diced onion, and minced garlic into the slow cooker.
Pour the beef broth and Worcestershire sauce over the meat and vegetables. Sprinkle in the paprika, salt, and black pepper.
Stir once to combine, then cover and cook on low for 8 hours.
About 20 minutes before the beef finishes cooking, bring a large pot of salted water to a boil and cook the wide egg noodles according to package directions. Drain and set aside.
Turn off the slow cooker and stir the sour cream into the beef mixture until the sauce is smooth and creamy.
Divide the noodles among four bowls, spoon the beef and mushroom sauce over the top, and finish with chopped parsley.