Makes one 9-inch or 11-inch tart
For this tart, select dark brown cremini mushrooms, which have a slightly more complex and fuller flavor than the common cultivated white mushroom. The cremini mushrooms’ earthy flavor balances the tanginess of the crème fraîche and makes for a memorable tart.
- All-Butter Pie Crust for single crust, fitted into a 9-inch or 11-inch tart pan and chilled.
- 2 tablespoons unsalted butter
- 3 to 4 leeks, white parts only, cleaned and thinly sliced
- 1/4 cup chicken stock
- 1/4 teaspoon kosher salt
- 1/4 teaspoon freshly ground black pepper
- 10 to 12 medium cremini mushrooms (6 to 7 oz), thinly sliced
- 3/4 cup (6.1 oz) crème fraîche
- 1/4 cup (2.1 oz) heavy cream
- 2 large eggs
- 1 cup (3 oz) coarsely grated Gruyère
- Preheat the oven to 400°F and set the rack in the lowest position.
- Line the chilled crust with lightly oiled or sprayed parchment and fill with weights. Partially blind bake the crust until it is a matte, pale golden color, 15 to 20 minutes. Transfer the crust to a cooling rack and remove the weights and parchment. Reduce the oven temperature to 350°F.
- In a medium sauté pan, melt 1 tablespoon of the butter over medium heat. Add the leeks and sauté until translucent and softened, 8 to 10 minutes. Reduce the heat to low and stir in the chicken stock, salt, and pepper. Simmer until almost all of the liquid has evaporated and the leeks are tender, about 15 minutes. Remove from the pan, transfer to a medium bowl, and set aside to cool.
- In a medium sauté pan, melt the remaining 1 tablespoon butter over medium heat. Add the mushrooms and sauté over medium heat until they have released their liquid and softened, 4 to 5 minutes. Remove the pan from the heat. Set aside.
- In another medium bowl, combine the crème fraîche, heavy cream, and eggs and whisk until thick and smooth.
- Sprinkle half of the cheese over the bottom of the prepared crust and arrange the leeks and the mushrooms in an even layer over the cheese. Pour the crème fraîche mixture over the filling and sprinkle with the remaining cheese.
- Bake until the center of the tart is just set and the edges are golden brown, 20 to 25 minutes. If more top color is preferred, switch the oven to a broil setting and broil until the cheese starts to brown, 3 to 4 minutes.
- Remove the tart from the oven and place it on a cooling rack. Serve warm or at room temperature.