1 1/2 lbs. ground beef
1 sm. onion, chopped
1/2 tsp. salt
1/4 tsp. pepper
1 (10 3/4 oz.) can cream of mushroom soup
1 c. sour cream
2 tbsp. catsup
2 tbsp. Worcestershire sauce
2 c. shredded Mozzarella cheese
1/2 lb. cooked noodles
1 sm. can mushroom pieces (optional)

Microwave ground beef and onions on high for 8-10 minutes. Stir to break up meat after 4 minutes. Drain.

Mix soup and sour cream. Add remaining ingredients except cheese.

Combine ground beef and soup mixtures in shallow 2-quart casserole dish.

Microwave, uncovered, 15 minutes at 70% power. Turn once.

Sprinkle with cheese and microwave 4-5 minutes at 70% power or until cheese melts.

Let stand 5 minutes before serving.