Preheat your oven to 375°F (190°C) and lightly spray a baking dish with nonstick cooking spray.
Cut the tops off the bell peppers and remove the seeds carefully.
In a skillet over medium heat, sauté the onion and garlic until fragrant. Add ground meat and cook until browned; drain excess fat.
In a bowl, combine the cooked meat mixture with rice, diced tomatoes, salt, pepper, and any additional seasonings.
Generously stuff each pepper with the filling mixture and place them upright in the prepared baking dish.
Cover the baking dish with aluminum foil and bake for about 30 minutes. Remove the foil, sprinkle cheese on top, then bake uncovered for an additional 10 minutes.