There isn't much more to say about this recipe other than it is THE BOMB. I absolutely, big time heart it. It's a recipe that I found on AllRecipes several years ago and modified a little bit to improve on the original, if that is even possible.
I made it for a group this weekend, and everyone asked for the recipe. It makes a TON, so if you're cooking for 5 or less people, I would half it. This recipe easily feeds 10.
1 pound (1 box) ziti pasta
1 onion, chopped
1 pound ground beef
(2) 26-oz jars spaghetti sauce
6 oz. sliced provolone cheese
1.5 cups sour cream
6 oz. shredded mozzarella
Preheat oven to 350 degrees; grease 9x13 baking dish.
Boil a large pot of water and cook ziti according to box instructions (about 8-9 minutes); drain.
In a large skillet, brown ground beef and chopped onion over medium heat.
Add spaghetti sauce; simmer 15 minutes.
Layer ingredients in baking dish as follows (listed in order of bottom to top layers): 1/2 of the ziti, 1/2 of the sauce, provolone slices, layer of sour cream (spread over provolone slices), remaining ziti, remaining sauce, shredded mozzarella. Sprinkle with Parmesan cheese.
Cover and bake in preheated oven 30-45 minutes, or until cheese is melted and all ingredients are warmed through.