Dried wild mushrooms are often available in the produce section, but 4 ounces of fresh mushrooms can be substituted. Swiss cheese can be substituted for the Gruyère.
Serves: 8Hands-on: 30 minutesTotal: 1 hour 35 minutesDifficulty: Medium
- 1⅔ cups all-purpose flour
- ¼ tsp. baking powder
- ½ tsp. salt
- 2 oz. Parmesan cheese
- 8 oz. unsalted butter (1 stick), cubed and chilled
- 2 Tbsp. ice water
- 1 tsp. white vinegar
- ½ oz. dry wild mushrooms
- 1 cup boiling water
- 2 Tbsp. olive oil, not extra-virgin
- 1 medium onion, sliced
- 1 pound button mushrooms, sliced
- 2 cloves garlic, minced
- 2 Tbsp. all-purpose flour
- 2 Tbsp. lemon juice
- 2 egg yolks
- ½ tsp. salt
- 1 cup Gruyère cheese, shredded
- ½ tsp. fresh thyme, chopped
- For the dough: In a large bowl, whisk together the flour, baking powder, and cheese. Add the butter and rub it into the flour with your fingers until 30 percent of the fat is pea-sized, while the rest is blended well. Add the water and vinegar and mix until the dough forms a rough ball. Add more water, a few drops at a time, if needed.
- Turn the dough out onto a lightly floured surface and form a disc. Wrap in plastic and chill for at least 30 minutes or up to 3 days.
- Heat the oven to 350°F.
- Remove dough from the refrigerator for 10 minutes to warm up. Roll out on a lightly floured surface to a ⅛" thick, 11" circle, turning the dough often to make sure it does not stick. Dust the surface with additional flour if needed. Fold the dough in half and place into a 9-inch tart pan with 1" sides. Unfold and carefully press the dough into the pan. Press the dough against the edge of the pan to trim.
- Line the tart with parchment paper or a double layer of aluminum foil and add pie weights or dry beans. Bake for 12 minutes, then remove the paper and weights and bake for an additional 10 to 15 minutes, or until the crust is golden brown all over. Remove from the oven and set aside to cool.
- For the filling: Combine the dry mushrooms with the water. Let stand for 10 minutes, or until rehydrated. Drain the mushrooms, reserving the liquid, and chop well.
- In a large skillet over medium heat, add the olive oil. Once the oil shimmers, add the onions and cook until softened, about 5 minutes. Add the button mushrooms and cook until tender, about 5 minutes. Add the garlic and rehydrated mushrooms and cook until fragrant, about 30 seconds.
- Add the flour to the mushrooms and cook for 1 minute. Stir in ½ cup of the reserved mushroom liquid with the lemon juice and cook, stirring constantly, until thickened. Reduce the heat to low.
- Whisk together ¼ cup of the reserved mushroom liquid with the egg yolks. Whisk the mixture into the mushrooms. Increase the heat to medium and cook until the liquid coats the back of a spoon. Stir in the salt. Pour into the tart shell. Sprinkle the top with the cheese.
- Set oven to broil and place oven rack in the uppermost position. Broil tart until cheese is melted and brown, about 1 minute. Remove and sprinkle with thyme. Serve warm.