1. Prepare Oven, Dish, and Cook Pasta:

• Gather all your ingredients. Preheat the oven to 350°F (175°C).
• Butter a 9×13-inch baking dish thoroughly, or spray it well with non-stick cooking spray. Set aside.
• Bring a large pot of lightly salted water to a rolling boil. Add the dry ziti pasta and cook according to package directions until al dente (tender but still firm to the bite), usually about 8-10 minutes.
• Drain the cooked pasta well in a colander and set aside.

2. Make the Meat Sauce:

• While the pasta cooks, brown the ground beef and chopped onion in a large skillet over medium heat. Cook, breaking the meat apart with a spoon, until the beef is fully browned and the onion is softened.
• Drain off any excess fat from the skillet. Season the meat mixture with salt and pepper to taste.
• Stir in the two jars of spaghetti sauce. Bring the sauce to a simmer and let it cook gently for about 15 minutes to allow the flavors to meld.

3. Assemble the Baked Ziti Layers:

• Layer 1 (Ziti): Spread half of the cooked and drained ziti evenly over the bottom of the prepared 9×13-inch baking dish.
• Layer 2 (Provolone): Arrange the slices of provolone cheese in a single layer over the ziti.
• Layer 3 (Sour Cream): Carefully spread the 1 ½ cups of sour cream evenly over the provolone cheese layer.
• Layer 4 (Meat Sauce – First Half): Spoon about half of the prepared meat sauce over the sour cream layer.
• Layer 5 (Ziti – Remaining): Add the remaining cooked ziti over the meat sauce.
• Layer 6 (Mozzarella): Sprinkle the shredded mozzarella cheese evenly over this ziti layer.
• Layer 7 (Meat Sauce – Remaining): Top with the remaining meat sauce, spreading it to cover the mozzarella and ziti.
• Layer 8 (Parmesan): Sprinkle the grated Parmesan cheese evenly over the very top of the casserole.

4. Bake:

• Place the assembled casserole dish in the preheated oven.
• Bake uncovered for approximately 30 minutes.
• The Baked Ziti is done when it is heated through completely and the cheeses on top are melted, bubbly, and perhaps lightly golden brown in spots.

5. Rest and Serve:

• Let the casserole cool in the dish on a wire rack for about 15 to 20 minutes before cutting and serving. This crucial resting time allows the layers to set and the sauce to thicken slightly, making it much easier to serve neat portions.
• Slice into squares and serve hot. Enjoy this comforting classic!