Preheat the oven to 375°F (190°C).

In a skillet over medium heat, cook the ground beef until browned. Drain excess fat.

Add the chopped onion and minced garlic to the skillet, cooking until the onion is translucent.

Stir in the cooked rice, diced tomatoes, Italian seasoning, salt, and black pepper. Mix well and remove from heat.

Stuff each bell pepper with the beef and rice mixture, packing it in tightly.

Place the stuffed peppers upright in a baking dish. Sprinkle shredded cheese on top of each pepper.

Cover the dish with aluminum foil and bake for 25 minutes. Remove the foil and bake for an additional 5 minutes until the cheese is bubbly.

Remove from the oven and let cool for a few minutes before serving.