In a large skillet, melt butter over medium heat.
Add chopped onion and garlic, cooking until softened.
Add ground beef and cook until browned. Drain excess fat if needed.
Stir in mushrooms and cook for another 3 minutes.
Sprinkle flour over the beef and stir well.
Gradually add beef broth and Worcestershire sauce, stirring continuously.
Simmer for 10 minutes until the sauce thickens.
Lower heat and stir in sour cream, salt, and pepper.
Serve over cooked egg noodles and garnish with parsley.