Baked Ziti

1 lb dry ziti pasta
1 onion
1lb lean ground beef
2 (36oz) jars spaghetti sauce
6 oz sliced provolone cheese
1 1/2 c sour cream
6 oz shredded mozzarella cheese
2 t grated Parmesan cheese

Bring a large pot of lightly salted water to a boil. Add ziti pasta, and cook until al dente, about 8 minutes. Drain.

In large skillet brown onion and ground beef over medium heat. Add spaghetti sauce and simmer 15 min.

Pre heat oven to 350 degrees. Butter a 9"x13" pan. Layer as follows:
1/2 boiled and drained ziti, provolone cheese, sour cream, 1/2 sauce mix, remaining ziti, mozzarella cheese and remaining sauce mix. Top with Parmesan cheese.

Bake for 30 minutes covered or until cheese is melted.