In a 10 inch or larger skillet with high sides, add the ground beef and onion and cook over medium heat until no pink remains. Drain any excess grease.
Add the garlic, cumin, salt, pepper, bell peppers, water, diced tomatoes, tomato sauce and rice to the skillet and stir to combine.
Cover with a lid and bring to a gentle simmer. Cook on medium low about 20 minutes, stirring once or twice until the rice is tender.
Turn off the heat. Top with cheese and cover with the lid until melted; about 5 minutes.
The casserole will thicken as it cools. Serve warm.