Set the oven's temperature to 425 degrees Fahrenheit.
Combine the meatballs, marinara sauce, water, uncooked pasta, salt, and crushed red pepper in a large baking dish. To make sure the pasta is coated evenly, give it a good stir.
Bake the dish in the oven for half an hour after securely covering it with aluminum foil.
Take off the foil and give the mixture a good swirl. Make sure the pasta is cooked through. Al dente, or soft but firm, is the ideal cooking temperature. Recover and bake for another 5 to 10 minutes if necessary.
Take out of the oven and carefully take off the aluminum foil. Cover the casserole with a layer of cheese.
Bake, uncovered, for a further 5 to 10 minutes, or until pasta is soft and cheese is melted.
Before serving, let the dish rest for five minutes. If desired, top with chopped fresh parsley or parmesan cheese.