Preheat oven to 375°F (190°C). Spray a 9x13 inch baking dish with olive oil or cooking spray.
Heat olive oil in a large skillet over medium heat. Add the chicken sausage (or ground chicken) and cook until browned, breaking it up with a spoon as it cooks.
Add the onion and peppers to the skillet and cook for 5-7 minutes, until softened.
Stir in the diced tomatoes, scraping up any browned bits from the bottom of the pan. Cook for 1 minute more.
In a large baking dish, combine the cooked brown rice, cauliflower rice, cooked chicken sausage mixture, and vegan parmesan cheese. Stir in salt, pepper, and garlic powder.
Bake for 30-40 minutes, or until heated through and edges are golden brown and crispy.
Serve hot and enjoy!