Preheat the broiler. Place the onion, bell peppers and garlic cloves on a baking sheet. Broil 3 inches from heat for 7 minutes or until blackened, turning frequently. Transfer to a paper bag, close tightly and let stand 15 minutes or until soft. Scrape off outside skins. Chop the onion and garlic; seed and chop the peppers. You will have about 2 cups of vegetables. Preheat oven to 350 degrees and spray a 13x9x3 inch-baking dish with nonstick cooking spray. In a large bowl, mix the beef, veal, vegetables, egg, chili sauce, breadcrumbs, 1/2 cup of the cheese and the black pepper. Mix with your hand until well combined. Transfer to the baking dish and pat into a 12x7 inch loaf, mounding it slightly in the center. In a small bowl, with an electric mixer set on medium-high, whip the hot potatoes with the remaining 1 cup of cheese, the chives and the butter until fluffy and pipe or spoon on top and sides of the loaf. Bake for 1 hour or until a meat thermometer inserted into the center of the meat loaf registers 145. Let stand for 10 minutes before serving.