Preheat the oven to 400 degrees F. Grease a glass baking dish with butter. In a small mixing bowl, combine the bread crumbs, parsley, and cheese. Season with salt and pepper. Mix well. Set aside. Season the potatoes and onions with salt and pepper. Place a layer of potatoes on the bottom of the prepared pan. Place a layer of onions over the potatoes. Sprinkle 1 tablespoon of the flour over the onions. Place half of the herring over the onions. Repeat the layering process with the remaining potatoes, onions, flour, and herring. Pour the milk over the herring. Sprinkle the top with the bread crumb mixture.
Put some salt in bottom of small bowl. Place fish skin down. Continue layering fish and salt finishing with a layer of salt. Put weight (dish or plate) on top and refrigerate for 4 to 5 days. Wash herring well and skin. Soak in cold water 1 hour, changing 3 to 4 times. Cut in 1-inch pieces. Drain and pat dry. Boil 3 tablespoons water with 1 teaspoon allspice. Add sugar, vinegar, bay leaves and pepper. Mix until sugar is dissolved. In a one quart jar put 2 cups pickling solution, some onions and herring pieces, laying them and topping with onions. Fill to top with solution. Keep in tightly closed jar in refrigerator 2 to 3 days until ready to serve.
Recipe from The Taste of Gloucester: A Fisherman's Wife Cooks, by The Fishermen's Wives of Gloucester, The Cape Ann League of Women Voters, published by Gloucester Cookbook Committee, 1976