Skin and bone a haddock, leaving meat in two fillets. Remove to buttered plank, sprinkle with salt and pepper, brush over with melted butter and bake thirty minutes. Garnish with mashed potatoes, outlining the original shape of the fish, making as prominent as possible head, tail, and fins. Bake until potatoes are well browned, when fish should be thoroughly cooked. Finish garnishing with parsley and slices of lemon sprinkled with finely chopped parsley.