Preheat oven to 350 degrees.
In a medium-size skillet, sauté ground beef and onions. Once cooked, add in the rice, diced tomatoes, taco seasoning, and 1 ½ cups of cheese. Mix well and set aside.
Prepare the peppers by cutting off the tops and taking out the seeds. Rinse and place into your iron skillet.
Fill each pepper with the meat and rice mixture. Add about an inch of water to the iron skillet. This will prevent the peppers from sticking to the pan.
Place in oven and cook for 30-35 minutes. Take out of the oven and sprinkle the remaining cheese on the top of each one. Place back in the oven for 3-5 minutes or until cheese is melted.
Serve with any additional toppings and Enjoy!