Bring a large pot of water to boil for the noodles.
Sautee mushrooms, garlic and onions. While the water is heating up, cook mushrooms, onions and garlic in butter in 10-inch skillet over medium heat, stirring occasionally, until onions are tender; remove from skillet. If using a bouillon cube, start preparing it now.
Cook noodles. When the water comes to a full boil, add the egg noodles and cook per package instructions. Strain and set aside when cooked through.
Brown beef and add broth, Worcester and mustard. Brown beef in the skillet the onions were cooked in. If using ground beef, drain off most of the fat after the beef is cooked through. Then add in most of the broth, the mustard and Worcestershire sauce. Heat to boiling; reduce heat.
Add cream of mushroom soup or make white sauce. Combine all and serve. Stir remaining broth into flour; stir into beef mixture. Add onion mixture; heat to boiling, stirring constantly. Boil and stir 1 minute. Stir in sour cream; heat until hot (do not boil). Serve over noodles.
