Preheat you oven to 425F and lightly grease a 9"x13" casserole dish.
Place the uncooked pasta and the thawed meatballs into the baking dish. Pour the tomato sauce and the water over the ingredients and sprinkle in the dry oregano and salt. (Skip to step 4 if you are not adding additional vegetables.)
Add the chopped mushrooms and bell pepper to the dish and mix everything together until all the ingredients are well distributed.
Mix the ingredients in the baking dish until they are all evenly distributed. Cover the dish tightly with aluminum foil and bake in the preheated oven for 35 minutes.
Remove the foil from the baking dish and give the casserole a good stir. Sprinkle the grated cheese all over the top of the casserole and place back into the oven for 10 minutes.
Remove from the oven and let it rest for 5 minutes before serving. Sprinkle the optional fresh basil over the top and serve.