1 pound dry ziti pasta
1 chopped onion
1 pound lean ground beef
2 (28- ounces) spaghetti sauce
6 ounces provolone cheese, sliced
1½  cups sour cream
6 ounces mozzarella cheese, shredded
2 tablespoons grated Parmesan cheese

Bring a large pot of lightly salted water to a boil. 

1. Add ziti pasta, and cook until al dente, about 8 minutes.

2. Drain. 

3. In a large skillet, brown onion and ground beef over medium heat. 

4. Add spaghetti sauce, and simmer 15 minutes. 

• Preheat the oven to 350º F (175º C). 

• Butter a 9x13 inch baking dish. 

Layer as follows: 

1. ½ of the ziti, Provolone cheese, sour cream,

2. ½ sauce mixture,

3. Remaining ziti, mozzarella cheese and remaining sauce mixture. 

Top with grated Parmesan cheese. 

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