Bring a large pot of lightly salted water to a boil. Add ziti pasta until al dented. about 8 minutes
In a large skillet brown the onion and ground beef over medium heat. Add both jars of spaghetti sauce. and simmer about 15 minutes
Preheat the oven to 350 degrees. Butter a 9x13 pan, or lasagna pan. Layer as follows Half the ziti, Provolone cheese, sour cream, half the sauce. Remaining ziti mozzarella cheese and the remaining sauce mixture. Top with grated parmesan cheese
Bake for 30 minutes in a preheated oven or until cheeses are melted.