Description
Caramelized mushrooms top a ground walnut, garlic, and Parmesan filling in this rich, umami-forward, flaky tart. Suitable to bring to an upscale gathering, this tart is best served warm.
Ingredients
Units
Scale
- 1 3/4 cups raw walnut halves
- 4 Tbsps extra-virgin olive oil, divided
- 2 cups thinly sliced yellow onions
- 1 clove chopped garlic
- 1 cup grated Parmigiano Reggiano cheese (about 2 oz)
- 1 puff pastry sheet (from 1 17.3-oz package), thawed according to package instructions
- 1 lb wild mushrooms, such as chestnut, lion’s mane, oyster, baby king trumpet, or shiitake, trimmed and cut into 2-inch pieces
- 1 Tbsp fresh chopped rosemary
- 1 Tbsp sherry vinegar
- 1/2 tsp fine sea salt
- 1/2 tsp freshly ground black pepper
- 1/2 cup fresh flat-leaf parsley sprigs
Instructions
- Preheat the oven to 350°F.
- Place the walnuts on a standard-sized baking sheet, place in the oven until fragrant and roasted, about 13 to 15 minutes. Let them cool on the pan, about 10 minutes. Transfer 1 1/2 cups of the nuts to the bowl of a food processor and set aside. Reserve the remaining 1/4 cup nuts for the topping. Raise the oven temperature to 400°F.
- Meanwhile, heat a large cast-iron or nonstick skillet over medium heat. Add 1 tablespoon olive oil and the onions and cook, tossing a few times until the onions are soft and golden brown, about 8 minutes. Transfer the onions to the food processor with the nuts and let cool slightly, about 15 minutes.
- Add the garlic and Parmesan to the food processor, then pulse until the walnuts and onions are finely chopped.
- On a lightly floured surface, roll the puff pastry into a 10 x 12-inch rectangle. Then transfer to a parchment-lined standard baking sheet. Use the tines of a fork to prick the puff pastry all over leaving a 1-inch thick un-pricked border.
- Spread the walnut mixture over the top of the pricked part of the puff pastry. Bake until the puff pastry is golden brown and the walnut mixture has turned a richer brown color, 15 to 20 minutes. Transfer to a cooling rack.
- Meanwhile, heat a large cast-iron or nonstick skillet over medium heat. Add the remaining 3 tablespoons of olive oil and the mushrooms and cook, flipping a few times with a spatula until browned in parts, about 5 minutes.
- Add the rosemary to the mushrooms and cook, tossing occasionally just until fragrant, about 2 minutes. Drizzle the vinegar over and toss to combine. Season with salt and pepper. Top the prepared crust with the mushrooms, reserved walnuts, and garnish with parsley. Serve warm.