pre-heat the oven to 400 degrees. Place French bread halves on a baking sheet, cut side up. Pull off a few pieces of the inside of the bread to hollow it out a bit. Spread each French bread half with ¾ cup pasta sauce. Sprinkle cheese over the sauce. Sprinkle oregano, salt, and pepper over the cheese. Top with mushrooms and pepperoni.
Place into the oven and bake at 400 degrees for about 15 minutes. Remove from the oven and sprinkle with parmesan cheese. Cut into slices and serve.