Start by bringing a large pot of salted water to a boil. Add the 12 ounces of ziti pasta and cook until just al dente—about 8 to 9 minutes. Drain the pasta and set aside.
Heat 2 tablespoons of olive oil in a large skillet over medium heat. Add the chopped onion and sauté until translucent, about 5 minutes. Stir in the minced garlic and cook for another minute until fragrant.
Add the 1 pound of ground turkey, breaking it up with a spatula. Cook until browned and no longer pink, about 7 minutes. Season with salt, pepper, 1 teaspoon dried oregano, and 1 teaspoon dried basil.
Pour in the 24 ounces of marinara sauce and stir to combine. Let it simmer for 5 minutes to blend the flavors.
In a medium bowl, combine the 15 ounces of ricotta cheese, 1 cup shredded mozzarella, and 1 cup grated Parmesan cheese. Season lightly with salt and pepper.
Preheat your oven to 375°F (190°C). In your baking dish, spread a thin layer of the meat sauce on the bottom. Add half of the cooked ziti pasta, then dollop half of the ricotta cheese mixture over the pasta. Spoon half of the remaining meat sauce over the top. Repeat with the remaining pasta, ricotta mixture, and meat sauce. Finally, sprinkle the entire dish with 1 cup shredded provolone cheese.
Cover the baking dish with aluminum foil and bake for 20 minutes. Remove the foil and bake for another 10-15 minutes until the cheese is bubbling and golden brown on top. Let it rest for 5 minutes before serving.