01 - Bring a large pot of salted water to a boil. Cook ziti according to package instructions until al dente. Drain and set aside.
02 - While pasta cooks, heat a large skillet over medium heat. Add Italian sausage and cook, breaking it up with a wooden spoon, until well browned and cooked through. Drain excess fat if necessary.
03 - In a large mixing bowl, combine cooked ziti, browned sausage, marinara sauce, and ricotta cheese. Season with salt and freshly ground black pepper. Mix gently until evenly combined.
04 - Preheat oven to 375°F (190°C). Transfer the pasta mixture into a greased 9x13-inch baking dish. Evenly sprinkle shredded mozzarella cheese over the top.
05 - Bake uncovered for 30 minutes or until the cheese is melted, bubbly, and lightly golden. Allow to cool slightly before serving.