Preheat the oven to 375°F (190°C).

Cut the tops off the bell peppers and remove the seeds and membranes.

In a skillet over medium heat, cook the chopped onion until translucent.

Add the ground beef to the skillet and cook until browned. Drain excess fat.

Stir in the cooked rice, diced tomatoes, garlic powder, Italian seasoning, salt, and black pepper. Mix well.

Stuff each bell pepper with the meat and rice mixture.

Place the stuffed peppers in a baking dish and cover with foil.

Bake in the preheated oven for 25 minutes.

Remove the foil, sprinkle cheddar cheese on top of each pepper, and bake for an additional 5 minutes until cheese is melted.

Serve hot and enjoy!