Preheat oven to 350.
Slice tops off of your peppers and remove seeds and membranes.
In large pot, fill with water, add your peppers and bring to a boil and boil for about 5 minutes.
Remove with thongs and set aside.
In large saute pan brown your ground beef until no longer pink, drain.
Stir in cooked rice, 1/2 can tomato sauce, 1 cup cheese, minced onion, salt and pepper until combined and cheese is melted.
Add peppers to a baking dish and stuff evenly with mixture.
Pour remaining tomato sauce over tops of peppers and bake in oven for 15 minutes.
Remove from oven and sprinkle with remaining 1/2 cup cheese and return to oven for about 5 minutes until cheese is melted and starting to brown.