Preheat your oven to 400°F (200°C).
In a large, high-sided oven-safe pot or deep baking dish, add the thawed meatballs, marinara sauce, water, uncooked pasta, and Italian seasoning.
Stir everything together until the pasta is mostly submerged in the liquid.
Cover tightly with a lid or aluminum foil and bake for 35 minutes, stirring once halfway through if possible.
Remove the cover, sprinkle the mozzarella and Parmesan cheeses evenly over the top, and return to the oven.
Bake uncovered for an additional 10–15 minutes, or until the cheese is melted and bubbly.
Let the casserole rest for 10 minutes before serving so the sauce can thicken.
Enjoy!