Preheat oven to 375 F.
In a large skillet, crumble the beef and brown along with the onion. Drain any excess fat.
Add the mushrooms and bell pepper and cook for 3-5 minutes or until they are just starting to get soft.
Add the tomato sauce, tomato soup, garlic powder, dried oregano, chili powder, tomato paste and black pepper. Stir and reduce heat to a simmer and simmer for at least 10 minutes, the longer the more the flavors will meld. If the sauce gets too thick add a bit of water.
Cut bread in half lengthwise and scoop out as much of the bread as you can.
Transfer bread to a sheet of aluminum foil.
Fill insides with the meat mixture.
Top with cheese and cover in foil.
Place on a baking sheet and bake for 10 minutes until the cheese is melted.
Serve with lots of napkins.