Meatball casserole: tip and bake.

Preheat oven to 400 degrees.
Place the meatballs, jar of sauce, water, and Italian seasoning in a deep ovenproof casserole or skillet. Stir to combine.
Cover and bake for 35 minutes.
Top with cheese and bake for an additional 10-15 minutes. Let stand for 10 minutes before serving.