Preheat the oven to 350 degrees. Bring a large pot of water to a boil for the pasta. Salt the water, add the pasta and cook until almost al dente. Drain and return to the pot. Toss the pasta with the marinara, mozzarella and meat loaf. Transfer half the pasta mixture to a 1 1/2-qt. baking dish. Dollop with the ricotta, then top with the remaining pasta. Cover with foil.
Bake the pasta until heated through, about 20 minutes. Uncover, sprinkle with the Parmesan and bake until golden, about 15 minutes. Sprinkle with the parsley.