How to Make It
Preheat the oven to 350°. In a medium saucepan, cover the parsnips with the milk and cream and bring to a boil. Cover and simmer over moderately low heat until the parsnips are tender, about 15 minutes. Transfer the parsnips and their cooking liquid to a food processor. Add the butter and puree. Scrape the puree into a bowl, add the thyme and season with salt and pepper.
In a medium saucepan, combine the turkey with the gravy and vegetables and bring to a simmer over moderate heat. Season the mixture with salt and pepper and transfer to a 9-by-13-inch glass or ceramic baking dish. Spread the parsnip puree over the top. Sprinkle with the bread crumbs and bake for about 30 minutes, or until golden brown on top and bubbling underneath. Let stand for 10 minutes before serving.