1 1/2 pounds parsnips (5 to 6 medium parsnips)
1 tablespoon butter, plus more for buttering dish
2 tablespoons olive oil
4 ounces mixed fresh mushrooms, cleaned and sliced
3 leeks, white and light green parts, cleaned, halved lengthwise and sliced thin
1 tablespoon fresh thyme leaves
1/3 cup dry white wine
1 cup grated Parmesan cheese
1 1/2 cups heavy cream
Freshly ground pepper
Peel parsnips and slice about 1/4-inch thick on an extreme angle so as to get the largest slices possible. Butter a 12x8-inch inch baking dish and preheat the oven to 400°F.
In a medium skillet, warm the butter and olive oil over medium-high heat. Add mushrooms and leeks along with a pinch of salt and sauté, stirring occasionally, until they release all of their liquid and begin to brown. Stir in the thyme and white wine, and cook, stirring occasionally, until wine evaporates. Set aside.
Layer the ingredients into the baking dish: Begin with a single layer of parsnip slices, season with salt and pepper, then layer on half of the leek and mushroom mixture, and finally half of the Parmesan. Repeat with parsnips, more salt and pepper, the remaining leek and mushroom mixture, and most of the remaining Parmesan, reserving a little for the top.
The final layer should consist of the remaining parsnips. Pour the cream over and push down with the back of a spoon to submerge everything as much as possible. Sprinkle the remaining Parmesan on top and cover with foil. Bake for 30 minutes, then uncover and check for tenderness. When the parsnips are nearly tender, uncover and continue to bake uncovered for an additional 15 minutes, or until the top begins to brown and all the cream has been absorbed. Let sit for about 10 minutes before cutting and serving.
This recipe has been updated — originally published November 2006.