Preheat the oven to 350 degrees F. In a large bowl, soak the bread crumbs in the milk until softened. In a small skillet set over moderate heat, cook the onion in the oil, stirring, until softened. Transfer to the bowl. Add the meat, grated cheese, egg, tomato sauce, parsley, and salt and pepper, and gently mix to combine.
In an oiled baking dish, arrange half the meat, patting it down into a flattened loaf shape. Arrange enough of the salami over the meat to cover it completely, add a row of egg halves down the center, and cover with a layer of the provolone and ham. Top with the remaining ground meat, forming the mixture into a loaf. Pour the ketchup mixture over the loaf and sprinkle with the bread crumbs. Bake for 1 hour, covered with foil. Remove the cover and bake for 30 minutes more, basting with the pan juices. Let stand for 15 minutes before slicing.