1. Heat a large skillet on medium heat and add butter. Once butter is melted, add ground beef and onion. Cook until meat is well browned. Add mushrooms and saute 2 to 3 minutes. Add garlic and cook another 30 seconds. Add flour and cook, stirring frequently, for 5 minutes.
2. Add soup, reduce heat to medium-low and cook 10 minutes, stirring occasionally. At end of 10 minutes, add sour cream and mix well. Heat thoroughly. Serve over hot egg noodles.
