DIRECTIONS
1. Bring a large pot of lightly salted water to a boil. Add ziti pasta, and cook until al dente, about 8 minutes; drain.
2. In a large skillet, brown onion and ground beef over medium heat. Add spaghetti sauce, and simmer 15 minutes.
3. Preheat the oven to 350 degrees F (175 degrees C). Butter a 9x13 inch baking dish. Layer as follows: 1/2 of the ziti, 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 minutes in the preheated oven, or until cheeses are melted.
I didn't make any changes to the recipe with the exception of how I layered it. I read some of the other reviews and decided to put the sauce mixture directly on top of the ziti, then add the cheese, sour cream and so forth. I even stirred the bottom layer of ziti and sauce together before I added anything else just to make sure that the sauce ran all through the noodles