Baked Ziti

1 pound dry ziti pasta
1 onion, chopped
1 pound Italian sausage ( or ground beef...I like sausage better)
2 teaspoons minced garlic
2 teaspoons Italian seasonings
2 (26 ounce) jars spaghetti sauce ( I used one Garlic and Onion and one Sausage)
6 ounces provolone cheese, sliced ( 9 rounds)
1 1/2 cups sour cream
8 ounces mozzarella cheese, shredded
grated Parmesan cheese

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 sausage (or beef ) over medium heat. Add minced garlic and cook for a minute or so. Add spaghetti sauce and Italian seasonings, and simmer 15 minutes.
3. Preheat the oven to 350 degrees. Butter a 9x13 inch baking dish. Layer as follows: 1/2 of the ziti, 1/2 sauce mixture, Provolone cheese, sour cream, remaining ziti, remaining sauce mixture and then mozzarella cheese. Top with grated Parmesan cheese.
4. Bake for 30 minutes in the preheated oven, or until cheeses are melted. You may want to cover it for the first 20 minutes with foil and then let the cheese melt and brown for the last 10 minutes.