Cut the tops off the bell peppers and remove the seeds and membranes.
In a large bowl, combine the ground beef, cooked rice, diced tomatoes (with juice), Parmesan cheese, Italian seasoning, salt, and pepper. Mix well.
Stuff the pepper cavities evenly with the meat mixture.
Place the stuffed peppers in a baking dish. Add about 0.5 inch of water to the bottom of the dish.
Cover the baking dish with foil and bake for 30 minutes.
Remove the foil, sprinkle the mozzarella cheese over the top of each pepper, and bake for another 10 minutes, or until the peppers are tender and the cheese is melted and golden.
Let stand for a few minutes before serving.
Notes
Serve with a side salad or crusty bread for a complete meal.