Mashed Root Vegetable Casserole

Mashed Root Vegetable Casserole
A sort of crustless cottage pie, this Mashed Root Vegetable Casserole has “comfort food” written all over it. Mashed yellow potatoes, celeriac, and parsnips crown a sausage filling laced with allspice and thyme. This is what you want to serve when the leaves have all browned and the woodstove is just getting going for the season.

Mashed Root Vegetable Casserole
Makes 8 to 10 servings
  • For the mashed topping:
  • ½ teaspoon plus a pinch of sea salt
  • 1½ pounds celeriac, peeled and cubed
  • 1½ pounds yellow potatoes (such as Yukon gold), peeled and cubed
  • 1 pound parsnips, peeled and cubed
  • 4 large eggs, separated
  • 6 tablespoons unsalted butter, melted
  • 1 cup heavy cream
  • 1 teaspoon dried thyme (or ½ teaspoon fresh)
  • For the meat filling:
  • 1 tablespoon olive oil
  • ½ medium onion, diced
  • 2 to 3 cloves garlic, minced
  • 2 pounds ground sausage
  • 2 teaspoons ground allspice
  • 2 teaspoons dried thyme (or 1 teaspoon fresh)
  • Several grinds of black pepper
  • Pinch of sea salt
  • 2 tablespoons all-purpose flour
  • For the topping:
  • 1 cup breadcrumbs
  • 2 tablespoons unsalted butter, melted
  1. Lightly oil a 9x13-inch baking pan. Set aside.
  2. Prepare the mashed topping: Bring 2 quarts of water and a pinch of salt to boil in a large saucepan. Add the celeriac, potatoes, and parsnips and simmer for 25 minutes. Drain the vegetables and place them in a large bowl.
  3. In a small bowl, beat the egg yolks. In a separate bowl, whisk the egg whites until frothy (beating the whites and yolks separately will add a bit of lightness to the finished casserole). Using a potato masher or large spoon, mash the cooked vegetables with the butter, cream, egg yolks and whites, the ½ teaspoon salt, and the thyme. Set aside.
  4. Prepare the sausage filling: Heat the olive oil in a large saucepan or skillet over medium heat. Add the onion and cook until slightly browned and fragrant, 4 to 5 minutes. Add the garlic and cook until lightly browned, 3 to 4 minutes. Add the sausage and stir to blend it into the onions and garlic. Cook for 5 minutes.
  5. Add the allspice, thyme, pepper, and salt. Continue cooking over medium heat until the meat has browned and is cooked throughout, 5 to 7 minutes longer. Add the flour to the meat mixture, stir to fully combine, and cook for an additional 3 to 4 minutes, until the meat thickens slightly. Remove from the heat and set aside.
  6. Assemble the casserole: Preheat the oven to 375°F.
  7. Spread the meat filling evenly across the bottom of the prepared baking pan. Spread the mashed vegetables evenly over the meat. Bake for 30 to 35 minutes, until the mashed topping just begins to brown.
  8. In a small bowl, add breadcrumbs and butter, stirring to combine. Spread the breadcrumbs mixture evenly across the top of the casserole. Return the baking pan to the oven and bake for an additional 15 minutes, until the breadcrumbs are golden brown and the dish feels firm in the center.
  9. Cool for at least 15 to 20 minutes or up to 30 minutes before serving.

Find more recipes, tablescapes, and seasonally inspired entertaining ideas in our October 2017 issue. Pick up your copy at newsstands and online now!