Brown the ground beef and onion together. Drain off the fat.
Add the spaghetti sauce and stir to mix.
Cook mini ziti noodles according to package directions.
Preheat the oven to 350 degrees.
Spray a 9x13 pan with cooking spray.
Spread half the noodles in the bottom of the dish.
Layer the provolone cheese, sour cream and then half the sauce on top.
Add the rest of the ziti.
Sprinkle 6 ounces of shredded mozzarella over top the ziti.
Top with the remaining sauce, parmesan cheese and the remaining mozzarella.
Bake at 350 degrees for 35 minutes.
If you'd like the top to get a touch of brown, broil the casserole for 2-3 minutes on high. Watch carefully!
The calories shown are based on the recipe being divided into 15 servings, with 1 serving being 1/15 of the recipe. Since different brands of ingredients have different nutritional information, the calories shown are just an estimate.