Mushroom and Walnut Tarte Tatin

• Size: Makes one 9-inch (23-cm) tart; 4 to 6 servings.

Ingredients:

• Mushroom Filling:
  • 3 tablespoons goose or duck fat or extra virgin olive oil
  • 1½ pounds (625 g) cultivated or wild mushrooms, trimmed and cut into thick slices
  • Sea salt
  • 1 cup (10 g) flat-leaf parsley leaves, gently packed
  • 1 teaspoon fresh thyme leaves
  • 3 garlic cloves, minced
  • ½ cup (50 g) walnut pieces, lightly toasted and minced
  • Freshly ground white pepper to taste
• Walnut Oil Vinaigrette:
  • 1 tablespoon fresh lemon juice
  • Fine sea salt to taste
  • ¼ cup (60 ml) walnut oil, preferably Leblanc brand
• Garnish: Fleur de sel

Instructions:

1. 1. Preheat the oven to 425°F (220°C). Heavily oil a 9-inch (22.5-cm) tarte Tatin pan or a heavy ovenproof skillet.
   2. Roll out the pastry on a lightly floured surface into an 11-inch (28-cm) round. Place the round on a parchment paper–lined baking sheet and refrigerate for at least 30 minutes and up to several hours. The pastry can also be frozen at this point.
   3. Heat the goose fat in a 12-inch (30-cm) nonstick skillet over moderate heat until hot but not smoking. Add the mushrooms, season lightly with salt, and sauté just until they wilt and begin to give up their juices, about 5 minutes.
   4. Mince half the parsley.
   5. Reduce the heat and add the thyme, garlic, the minced parsley, and half of the minced walnuts. Cook, stirring regularly and shaking the pan, until the mushrooms have reabsorbed most of their juices, a minute or two more. Season generously with salt and pepper and remove from the heat.
   6. Transfer the mushroom mixture to the tart pan or skillet. Place the filled pan on a baking sheet. Remove the pastry from the refrigerator and place it on top of the mushroom mixture, gently pushing the edges of the pastry down around the edge of the pan. Return to the oven and bake until the pastry is golden, 20 to 25 minutes.
   7. While the tart is baking, prepare the vinaigrette: In a small bowl, combine the lemon juice and salt and whisk to dissolve the salt. Add the walnut oil and whisk to combine. Taste for seasoning.
   8. Remove the tart from the oven. Immediately place a serving platter with a lip atop the skillet. Quickly but carefully flip the skillet so that platter is on the bottom. Using a spatula or an offset knife, lift the skillet off the platter and let the burst of steam float away, then remove the skillet from the platter. If any mushrooms stick to the pan, gently transfer them to the top of the pastry.
   9. Mince the remaining parsley and sprinkle atop the mushrooms with the remaining walnuts. Drizzle with the walnut oil vinaigrette, season
      with fleur de sel, and serve.

Note: When choosing cultivated mushrooms, look for those that are slightly open near the head of the stem; they are more mature than those that are tightly closed and will offer more flavor. Note too, that during wild-mushroom season, you can substitute any mushrooms, including cèpes, chanterelles, or morels.