Preheat the oven to 400 degrees F. Bring a large pot of water to a boil, salt generously, and boil the pasta until al dente, tender but still slightly firm. Drain. In a large bowl, toss the cooked pasta with the marinara sauce, 1/2 cup of the Parmesan and the cubed mozzarella pieces. Season with the black pepper and red pepper to taste, and mix until well combined. Transfer the pasta to an oiled 9- x 13-inch baking dish. Cover the top of the pasta with the sliced mozzarella, and sprinkle with the remaining Parmesan. Bake until lightly browned and hot, about 30 minutes. Serve immediately.