Heat a large skillet over medium-high heat. Add the Italian sausage and cook, breaking it up with a spatula, until browned and no longer pink, about 5–7 minutes.
Drain excess fat from the skillet, then return the browned sausage to the pan.
Add the Italian seasoning, dried minced onion flakes, minced garlic, and 3/4 cup water to the sausage. Stir to combine and simmer for 5 minutes.
Stir in the tomato sauce and the cooked rice until evenly combined. Reduce heat to medium-low and heat, stirring occasionally, for 5–10 minutes until heated through.
Serve topped with grated Parmesan or shredded mozzarella cheese, if desired.
