Preheat the oven to 350°F. Spray a deep 13x9 inch casserole dish with cooking spray.
In a large, deep saute pan, heat oil over medium high heat.
Once the oil is hot, add the onion, bell pepper, and garlic. Saute until softened, approximately 5-7 minutes.
Add the cooked and drained cauliflower rice, diced tomatoes, pasta sauce, salt and pepper, and Italian seasoning. Mix well and simmer for 5 minutes.
Remove from the heat and stir in the parmesan. Transfer the mixture to the prepared casserole dish.
Add meatballs, distributing evenly. Top the casserole with mozzarella. Cover with tin foil and bake for 20 minutes.
Once done baking, switch the oven to broil and broil for 2-3 minutes or until the cheese is golden.
Top with fresh basil and serve!