In a large pot, saute onions and mushrooms on medium heat in olive oil. After they become tender, stir in garlic and cook until fragrant, about 1 minute.
Pour in 2 jars of marinara sauce, water, and spices. Stir and bring to boil. Reduce heat to medium-low. Add in cooked meatballs and cover.
Cook spaghetti to al dente, then toss with sauce and meatballs.
Notes
*I used two packages of this kind of meatballs. They were new to my grocery store so I gave them a whirl. SO GOOD!! Feel free to use frozen, cooked meatballs.**I used the Classico brand Tomato Basil Marinara.