Meaty Macaroni Bake

1 pound ground beef
1/2 C chopped onion
1 (16oz) jar spicy spaghetti sauce
1 (4oz) can mushroom pieces, drained
6oz macaroni, divided
1 C sour cream, divided
4oz sliced provolone cheese
4oz mozzarella cheese, shredded

Heat large skillet over medium-high heat. Add beef. Cook until brown and crumbly, about 5 minutes; drain fat. Add onion, cook 2 minutes. Stir spaghetti sauce into skillet. Simmer, covered, 5 minutes. Meanwhile, cook pasta according to package directions; drain. Preheat oven to 350. Spray baking dish with cooking spray. Layer half the pasta, half the sauce and half the sour cream in dish. Layer provolone over top. Repeat layers; top with mozzarella. Cover loosely with foil sprayed with cooking spray. Bake for 25 minutes; uncover. Bake 5 minutes more.