Step 1

Preheat oven to 375 degrees F.

Step 2

Heat oil in a large saucepan on medium heat. Add olive oil and then ground beef, mushrooms, onions, garlic, salt and pepper. Cook until ground beef is done. Mix in chopped parsley and 3 cups of tomato sauce. Bring to a boil and then remove from heat.

Step 3

Spread the extra cup of plain tomato sauce in bottom of a large baking dish. Place peppers with tops removed in baking dish. Spoon in ground beef mixture into each pepper. Sprinkle on parmesan cheese and then place pepper tops back on peppers. Cover dish tightly with aluminum foil and bake for 1 hour. Remove aluminum foil and bake for another 20-30 minutes or until peppers are soft.