Baked Ziti
1 pound dry ziti pasta or rigatoni
1 onion, chopped
1 pound lean ground beef
2 (26 ounce) jars spaghetti sauce
6 ounces provolone cheese, sliced
1 1/2 cups sour cream
6 ounces mozzarella cheese, shredded
3 tablespoons 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 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
• all the Provolone cheese
• sour cream
• 1/2 sauce mixture
• remaining ziti
• all the mozzarella cheese
  
• remaining sauce mixture
• top with grated Parmesan cheese
  

4.) Bake for 30 minutes in the preheated oven, or until cheeses are melted