Cook noodles as directed on package. Drain; cover to keep warm.
Meanwhile, in 12-inch nonstick skillet, cook beef over medium-high heat, stirring frequently, until thoroughly cooked; drain.
Stir in onion, mushrooms, garlic, salt and pepper. Reduce heat to medium. Cover; cook 5 to 8 minutes, stirring occasionally, until vegetables are tender.
Stir in soup and sour cream. Cook, stirring occasionally, until hot. Serve over cooked noodles. Sprinkle with parsley.