Heat a large skillet over medium-high heat for 2–3 minutes. Add 1 pound ground sausage and 1 teaspoon salt. Cook for 5–6 minutes, breaking up the sausage with a spatula, until browned.
Slice 1 ½ pounds zucchini cut into ¼-inch rounds (halved or quartered if large). Add zucchini to the skillet. Stir and cook for 2 minutes, until it just begins to soften.
Stir in 1 cup diced onion. Cook for a few more minutes until cooked through and the zucchini and onions begin to soften.
Stir in 1 tablespoon minced garlic, 1 teaspoon paprika, 2 teaspoons Italian herbs, ½ teaspoon onion powder, ½ teaspoon garlic powder, and ¼ teaspoon black pepper. Mix well so the sausage and vegetables are evenly coated with seasoning.
Pour in 2 (14.5-ounce) cans or 1 quart jar of diced tomatoes, including juices. Stir to combine. Bring to a gentle boil, then reduce the heat and simmer for 5 minutes to meld flavors.
Choose your method of rice: Pre-soaked or cooked rice: Stir in 3 cups cooked or pre-soaked rice. Mix until evenly distributed. Cover and let rest for 5 minutes so the rice absorbs the flavors. Instant rice: Stir in 1 cup instant rice with 14.5 ounces water or broth. Increase heat to medium-high and bring to a gentle boil. Turn off heat, cover, and let rest for 5–7 minutes, until rice is tender and liquid absorbed. Sprinkle 1 cup shredded cheddar cheese evenly over the casserole. Cover and let sit for 2–3 minutes until melted.
Optional oven method: Transfer mixture to an oven-safe dish, top with cheese, and place under the broiler for 1–3 minutes. Watch closely until the cheese is melted, bubbly, and lightly golden.
Serve warm with extra cheese if desired.