Creamy Seafood Casserole
Heat oven to 375° F. Heat 2 tablespoons of the oil in a large pot over medium heat. Add the onion, carrots, parsnips, celery, and ½ teaspoon salt and cook, stirring occasionally, until tender, 15 to 18 minutes. Sprinkle with the flour and cook, stirring, for 1 minute (do not let darken). Add the wine and simmer until nearly evaporated.Add the cream, ½ teaspoon salt, and ¼ teaspoon pepper and bring to a boil. Remove from heat, stir in the parsley, and transfer to an 8-inch square baking dish.Meanwhile, place the potatoes in a medium saucepan and add enough cold water to cover. Bring to a boil and add 1 teaspoon salt. Reduce heat and simmer until tender, 15 to 18 minutes. Reserve ¾ cup of the cooking water, drain the potatoes, and return them to the pot. Add ¼ cup of the remaining oil, ½ teaspoon salt, ¼ teaspoon pepper, and ¼ cup of the reserved cooking water and mash (adding more cooking water, if necessary) until smooth.Nestle the fish and shrimp in the vegetable mixture and top with the potato mixture.In a small bowl, combine the bread crumbs and the remaining 1 tablespoon of oil and sprinkle over the potatoes. Place the dish on a rimmed baking sheet and bake until golden brown, 20 to 25 minutes.