In a large skillet over medium heat, heat the olive oil, butter, and garlic. Once the garlic is golden, remove and discard it. Add the onions and sauté until translucent.
Add the ground beef to the skillet. With the back of a spoon, break down the ground beef into smaller pieces. Cook until all the juices from the meat are gone.
Add the tomato sauce, season with salt and pepper. Lower the heat, cover, and cook for 20 minutes.
Meanwhile, slice the bell peppers in half lengthwise. Remove all the internal seeds. Clean and dry. Sprinkle with salt and pepper.
Butter an ovenproof pan.
When the tomato sauce is done, add the rice and mix well. Add the ½ cup of Parmesan cheese and mozzarella to the mixture.
Fill each half of the bell peppers with tomato and rice. Place them in the buttered dish; you may need two. Sprinkle the remaining 2 tablespoons parmesan cheese over the peppers.
Bake in the hot oven for 20 to 25 minutes, until the cheese is melted and the peppers are slightly soft.
Giangi's Kitchen provides nutritional information, but these figures should be considered estimates, as a registered dietician does not calculate them.