Baked Ziti

I love trying new recipes and I found this one a few years ago. I'm not sure where I got it from but it's a good one. Makes 8 servings. But, I feed 7 people with it last night and there is still enough for two more meals for my daughter and I. Not sure how they come up with the serving sizes but we had our plates full.

Ingredients:
1lb. dry ziti pasta
1 onion chopped
1lb. ground beef
2 (26oz.) jars of spaghetti sauce
6 oz. provolone cheese, sliced
1 1/2 cups sour cream
6 oz. mozzarella cheese, shredded
2 tablespoons parmesan cheese

1) Bring a large pot of lightly salted water to a boil. Add ziti pasta and cook until done. About 8 mins.
2)In a large skillet, brown onion and ground beef. Add spaghetti sauce and simmer 15 mins.
3)Preheat oven to 350 degrees. Butter 9 x 13" baking dish. Layer as follows:
half of ziti noodles, provolone cheese, sour cream, 1/2 sauce mixture, remaining ziti, mozzarella cheese and remaining sauce mixture. Top with grated parmesan cheese.
4)Bake for 30 mins.

I had a 32oz. jar of spaghetti sauce so I pureed a can of kidney beans and added that to the hamburger as well. I used whole wheat ziti noodles also. The kids never knew the difference. They loved it.