1 1/2 lbs. lean ground beef
1 egg
3/4 c. cracker crumbs
1/2 c. finely chopped onion
1/8 tsp. pepper
3 (8 oz.) cans tomato sauce
1 c. mushrooms
1 tsp. salt
1/2 tsp. oregano
2 c. shredded Mozzarella cheese

Combine meat, egg, crumbs, onions, salt, pepper, oregano, 1/3 cup tomato sauce. Shape into a flat rectangle about 10 x 12 inches on wax paper. Sprinkle mushrooms and cheese evenly over meat mixture and roll up like a jelly roll. Press ends to seal. Place in a shallow baking dish. Bake at 350 degrees for 1 hour. Drain off fat. Pour on remaining sauce and bake 15 minutes more.