Hamburger Pizza Casserole

1 lb ground beef
1/4 C chopped onion
1 sm jar spaghetti sauce
1 1/2 c shredded mozzarella
1/2 c sour cream
1 (8oz) can crescent rolls
1/3 c Parmesan cheese
2 Tbs Margarine (melted)

Brown beef and onion, drain. Stir in spaghetti sauce, heat until hot and bubbly. Combine cheese and sour cream. Pour hot meat mixture into greased 9x13 pan. Spoon cheese mixture over meat. Heat in 375 oven until bubbly. Place rectangle crescent rolls over cheese mixture. Spread margarine over rolls and sprinkle Parmesan cheese on top. Return to oven until rolls are golden brown.