This mushroom, leek, and Gruyère tart, made with puff pastry, topped with garlic and thyme-infused leeks and mushrooms and Gruyère cheese is an easy appetizer or light vegetarian entrée.
If vegetables were looking to elect a spokesperson, I’d nominate mushrooms. A bit of heat brings out the best in them, and, when things get downright hot, they maintain their composure, refusing to dissolve into incoherent mush. They work graciously with almost any herb, are effusively complimentary to dairy, and are as comfortable with fancy pastry as they are with a casual slice of toast.–Charmian Christie
“Love this recipe! Have tried it a few times and it is so tasty and easy. It’s my go to leek recipe now.!”–Jo
WHAT’S THE BEST WAY TO CLEAN LEEKS?
Leeks can be deceptively dirty…and you’re going to want to get them clean. They prefer sandy soil and because of their growth pattern, they have lots of layers, nooks, and crannies where sand and grit hide. Trim off the roots and dark tops, slice the remaining leek, and separate. Dump all of the pieces into a baking dish or deep bowl full of cool water and swish around to dislodge all the grit. The leeks will float while the dirt and sediment will fall to the bottom. Scoop out those clean leek bits and place them on a paper towel to drain.
Mushroom, Leek, and Gruyère Tart
- 1 sheet store-bought puff pastry preferably Dufour, defrosted according to package instructions
- 3 tablespoons (1 1/2 oz) unsalted butter
- 2 cloves garlic finely chopped or grated
- 2 sprigs fresh thyme leaves only
- 2 to 3 leeks white parts only, halved lengthwise and sliced into thin half-moons (about 2 cups)
- 16 ounces cremini mushrooms cut into 1-inch (25-mm) chunks
- Freshly ground black pepper to taste (optional)
- 3 ounces Gruyère cheese grated
- Preheat the oven to 425°F (218°C).
- On a sheet of parchment paper cut to fit a rimmed baking sheet, roll the puff pastry sheet into a 10-by-10-inch square, gently smoothing out any creases in the pastry. Using a sharp knife, lightly score the pastry, leaving a 1-inch border all along the outer edge and being careful not to cut all the way through the pastry. Carefully slide the parchment with the scored pastry onto a rimmed baking sheet and refrigerate while you prepare the topping.
- In a large skillet over medium heat, melt the butter. When it bubbles, toss in the garlic and thyme and cook for 1 minute. Add the leeks and cook until they begin to soften. Add the mushrooms and cook until they’re soft but not yet releasing any liquid. Dump the mushroom filling in a strainer situated over a bowl and let drain for a few minutes.
- Spoon the mushroom filling onto the pastry, being careful to stay inside the scored lines. Either reserve the strained mushroom liquid for making vegetable stock or discard it. Grind fresh black pepper, if using, over the topping.
- Bake the tart for 15 minutes, checking the puff pastry after 10 minutes. If the pasty is already golden brown, cover the exposed pastry edges with foil strips to prevent it from turning too brown. After the first 15 minutes, remove the tart from the oven and sprinkle it with the cheese. Bake for 5 to 7 minutes more, or until the cheese has melted and the pastry is golden brown. Again, it may be necessary to cover the outer edges with foil.
- Let cool for 5 minutes and then slice into squares or rectangles. This tart is best eaten as soon as it is cool enough to handle. (Any leftover mushroom leek tart can be wrapped and refrigerated, but the pastry will suffer. To reheat, pop under the broiler for a few minutes. Whatever you do, don’t reheat the tart in the microwave.)
Recipe Testers’ Reviews
I would file away this mushroom, leek, and Gruyère tart as an impromptu entertaining dish. The prep time is minimal, and the result is impressive. I love the mild oniony flavor of leeks that really shines through here. Prepping the vegetables took roughly 15 minutes, and the rest was simple.
This puff pastry tart was so delicious. It was easy to make, and I’d definitely make this mushroom leek tart recipe again. I purchased my puff pastry from a high-end grocery store where all the ingredients are natural, and the taste is “real.” If I was making this recipe again, I would definitely use a little more cheese. Definitely allow the tart to sit for 5 minutes before serving because the cheese is piping hot.
It’s pretty hard not to like this mushroom, leek, and Gruyère tart, as it comes together so easily using store-bought puff pastry. The light herb treatment of this recipe lets the delicate flavor of the leeks along with the earthiness of the mushrooms come through. With just a little planning ahead, it would work great for a party or as a vegetarian weeknight dinner. You can clean and trim the leeks the night before and finish the slicing and remaining prep in a snap. Save the tender but more yellow and green leek interiors for another project, using just the palest portions of your leeks for this tart. Since the amount of cheese is small, go for a nice, nutty Gruyère.
With so few ingredients in the tart, each one needs to sing. I liked the buttery flavor and overall texture of premium puff pastry (Dufour) better than than the brand that’s made with shortening (Pepperidge Farm). As you unfold the puff pastry, you’ll need to rejoin and roll the pastry to make a solid sheet. Lightly dusting parchment paper means you use very little flour, and the pastry was very close to the desired dimensions. A second sheet of parchment folded to exact measure works nicely as a cutting template and to make the border cuts and then can be used to cover the pastry in the fridge while preparing the filling. (The puff pastry trims can be used for cheese straws or cinnamon paniers to have with your morning coffee.) You can easily transfer the pastry to a larger cookie sheet for baking if you have juggled a smaller sheet to fit in a side-by-side fridge.
You don’t want to get the leeks browning, and your mushrooms aren’t supposed to give up too much liquid, so the timing is pretty accurate here. If you’re clever, you’ll slip a bowl under the strainer when you drain the mushrooms and capture that lovely mushroom and leek liquid for soup stock! You can fit the mixture in a 10-inch cast-iron skillet, but a larger skillet would ensure a drier result with less crowding and weeping of mushroom juices. I found that the second time I made this in the larger skillet and with more carefully cut mushrooms, less liquid drained off. The only adjustment to cooking time was I gave an extra 2 minutes at the end to get a more even golden color on the pastry, and I think it helped the bottom cook more thoroughly. Just watch it and check. I think a tiny amount of sherry vinegar (1 to 2 teaspoons) added toward the end of sautéing the leeks and mushrooms might brighten the flavor a bit. Now that I’ve made this twice, I would explore using maitake, oyster, or even beech mushrooms, though they’ll need only the slightest sauté.
One problem I pondered is that even after draining the excess liquid from the mushroom and leek mixture, the center piece that has no outer crust seems moister than you want. I had cut it into 9 slices. You could solve that by cutting once horizontally and then 4 times vertically, ending up with 8 slices. I also think that since the puff pastry from Dufour comes folded twice, you might consider making a couple of 6-by-10-inch tarts and then cut only across the short side so almost every piece has the same amount of crust.
I made this mushroom, leek, and Gruyère tart on a humid, rainy day, and the earthiness of the mushrooms and herbs perfectly complemented the ambiance. What is not to like about leeks, mushrooms, herbs, and cheese all atop puff pastry? It was an incredibly simple dish that produced huge flavors.
I baked the tart for about 12 minutes, then added the cheese and baked for another 3 minutes, as I was concerned about the pastry browning too fast. We ate this with a nice green salad dressed with a Dijon mustard vinaigrette and a nice cold Stella Artois beer. Very delicate and light. Brilliant.
I loved the simplicity of this mushroom, leek, and Gruyère tart—especially that it’s made with store-bought puff pastry, which makes it so approachable, even for a weeknight dinner. I subbed shallots for leeks since I couldn’t find them anywhere. It worked well, although I imagine the leeks give it a bit more color.
I found that the amount of filling this recipe made filled two 10-by-10-inch sheets of puff pastry. I’d also use an egg wash along the edge of the puff pastry as well as scoring it since mine took ages to come to a nice golden brown. There were no leftovers!
Disclaimer: The author, Charmian, is a friend of mine.
Very easy. Very straightforward. Very yummy. It took about 35 minutes from start to finish and makes a very good light dinner accompanied by a simple green salad. This mushroom leek tart recipe is a keeper!
To me, there’s nothing more appealing than the smell of garlic and leeks cooking in butter. This simple mushroom leek tart is a lovely, French-inspired dish that’s perfect for lunch or a light supper. The fresh thyme, garlic, leeks, and sliced mushrooms is made even more delectable when placed on top of a buttery, flaky puff pastry crust and finished with nutty Gruyère.
This mushroom, leek, and Gruyère tart made for a tasty meal with a salad. I had to adjust a few things while making this and would adjust a few more before making it again. The recipe calls for 2 sprigs of fresh thyme leaves. Two sprigs of my bunch of thyme would not have yielded enough for the amount of topping that was going onto the tart. I ended up using quite a bit more.
I had about a teaspoon’s worth of thyme leaves and could possibly have used a bit more. 1 pound of mushrooms was a bit too much. In addition, I would cut my mushrooms into smaller pieces next time. I think that I’ll try adding some pancetta to this when I make it again.
Originally published October 27, 2014