Heat a large skillet over medium-high heat. Add the Italian sausage and cook, breaking it up with a spatula, until browned and cooked through, about 6–8 minutes.
Drain excess fat from the skillet, then return the sausage to the pan.
Add the Italian seasoning, minced garlic, and dried minced onion flakes to the sausage; stir to combine.
Pour in the water, reduce heat to low, and simmer for 5 minutes to let flavors meld.
Stir in the tomato sauce and cooked rice. Cook over medium-low heat, stirring occasionally, until heated through, about 5–10 minutes.
Serve hot and top with parmesan or mozzarella cheese as desired.