French Onion and Mushroom Tart with Gruyere Cheese: A Flaky, Golden Showstopper!
By Jason Griffith
Imagine a golden, flaky puff pastry crust embracing a rich, savory filling of deeply caramelized onions, earthy mushrooms, and nutty, melted Gruyère cheese. This French Onion and Mushroom Tart with Gruyere Cheese is an absolute showstopper! It’s a sophisticated, comforting dish that’s deceptively easy to make, perfect for a leisurely brunch, an elegant appetizer, or a cozy dinner. Prepare to impress with this delightful blend of classic French flavors and effortless elegance.
Why I Love This Recipe
I’m utterly captivated by dishes that combine rustic comfort with refined presentation, and this tart perfectly embodies that. What I absolutely adore is the way the sweetness of the caramelized onions marries with the earthy richness of the mushrooms, all tied together by the nutty, gooey Gruyère cheese. The flaky puff pastry provides that irresistible buttery crunch, creating a symphony of textures in every bite. And the secret weapon, a splash of dry sherry, adds a layer of depth that elevates the entire tart. It feels incredibly gourmet, yet the use of pre-made puff pastry makes it remarkably accessible, transforming a simple bake into an unforgettable culinary experience.
Ingredients:
- 1 sheet puff pastry (about 14 oz), thawed according to package directions
- 12 oz sliced shiitake or cremini mushrooms
- 2 medium yellow onions, thinly sliced
- 1¼ cups grated Gruyere cheese
- ¼ cup dry sherry (such as Fino or Amontillado)
- 2 tbsp olive oil (or unsalted butter)
- Salt and freshly ground black pepper, to taste
- Optional: fresh thyme leaves for garnish
Swaps and Notes
- Puff Pastry: Ensure your puff pastry is thawed but still cold to handle easily. Do not let it get too warm, or it will be sticky. Ready-made puff pastry is key for this recipe’s ease.
- Mushrooms: Shiitake or cremini mushrooms offer the best earthy flavor. You can use a mix of both, or even add a few rehydrated dried porcini for extra depth.
- Onions: Yellow onions caramelize beautifully. You can use sweet onions (like Vidalia) for extra sweetness. Thin, uniform slices are important for even caramelization.
- Gruyère Cheese: Gruyère cheese is essential for its nutty flavor and excellent melting properties. You can also use Comté, Emmental, or a mix that includes some provolone or mozzarella for meltiness.
- Dry Sherry: Dry sherry adds a distinct, complex flavor to the caramelized onions. You can use dry white wine(like Sauvignon Blanc or Pinot Grigio) as a substitute, or a tiny splash of balsamic vinegar for depth, though the flavor profile will differ.
- Fat: Olive oil is suitable, but a mix of olive oil and unsalted butter can add more richness to the sautéed onions and mushrooms.
- Herbs (Optional): A sprinkle of fresh thyme leaves over the finished tart adds a beautiful aromatic touch that complements the flavors perfectly.
Instructions:
1. Prepare Puff Pastry: Preheat your oven to 400°F (200°C). Line a large baking sheet with parchment paper. Carefully unroll the thawed puff pastry sheet onto the prepared baking sheet. You can lightly score a border about ½ inch from the edge of the pastry (being careful not to cut all the way through) to create a crust, or simply leave it as is. Prick the center of the pastry with a fork a few times to prevent it from puffing up too much in the middle.
2. Caramelize Onions & Sauté Mushrooms: In a large skillet, heat 2 tablespoons of olive oil (or butter) over medium-low heat. Add the thinly sliced yellow onions. Sauté slowly, stirring occasionally, for about 15-20 minutes, or until the onions are deeply softened, translucent, and beautifully caramelized to a golden-brown color. Patience is key here for developing flavor. Once the onions are caramelized, add the 12 oz sliced shiitake or cremini mushrooms to the skillet. Increase the heat to medium and cook, stirring, until the mushrooms have released their liquid and browned, about 5-7 minutes. Pour in the ¼ cup dry sherry. Stir and scrape the bottom of the pan to deglaze, allowing the sherry to reduce and its flavors to infuse into the onions and mushrooms. Season the mixture generously with salt and freshly ground black pepper to taste. Remove from heat.
3. Assemble the Tart: Spread the onion and mushroom mixture evenly over the center of the puff pastry, staying within the scored border if you made one. Evenly sprinkle 1¼ cups of grated Gruyere cheese over the top of the onion and mushroom mixture, ensuring good coverage.
4. Bake the Tart: Place the baking sheet with the assembled tart into the preheated oven. Bake for 25-30 minutes, or until the puff pastry crust is golden brown and puffed up, and the Gruyere cheese is melted, bubbly, and lightly golden.
5. Cool & Serve: Remove the tart from the oven. Allow it to cool slightly on the baking sheet for about 5-10 minutesbefore carefully transferring it to a cutting board. This allows the cheese and filling to set slightly. Slice the tart into squares or wedges. Garnish with fresh thyme leaves if desired. Serve warm and enjoy this flaky, golden showstopper!
Tips for Success
- Cold Puff Pastry: Work with cold puff pastry to maintain its flakiness. If it gets too warm, chill it briefly.
- Score Border (Optional): Scoring a border helps create a defined, flaky crust around the edge of your tart.
- Prick Center: Pricking the center prevents the middle from puffing up too much and leaving little room for filling.
- Caramelize Onions Slowly: This is the most important step for developing deep, sweet flavor. Don’t rush it!
- Deglaze with Sherry: The sherry adds a wonderful depth and helps scrape up flavorful bits from the pan.
- Don’t Overload: Avoid piling the filling too high, as it can make the pastry soggy or difficult to bake through.
- Serve Warm: This tart is best served warm when the cheese is gooey and the pastry is flaky.
Serving Suggestions and Pairings
This French Onion and Mushroom Tart is elegant enough for a special occasion and comforting enough for a casual meal.
- Brunch Centerpiece: Serve it as the star of your weekend brunch, alongside fresh fruit or a simple green salad.
- Appetizer: Cut into smaller squares for a sophisticated appetizer. It would pair beautifully with French Onion Soup with Gruyère Cheese for a full French onion theme!
- Light Dinner: Serve with a crisp green salad tossed with a light vinaigrette.
- Wine Pairing: A crisp, dry Sauvignon Blanc, a light Chardonnay, or a dry Pinot Noir would complement the earthy mushrooms and nutty Gruyère.
- For other comforting, cheesy, or mushroom-forward dishes, explore these Chefmaniac.com favorites:
- Creamy Spinach Mushroom Lasagna
- Mushroom Ravioli with Spinach
- Philly Cheesesteak Casserole (for another savory bake with cheese and onion)
- This Baked Brie Appetizer Is My Favorite Effortless Way to Impress Guests (for another easy and impressive appetizer).
Storage and Leftover Tips
This tart is best enjoyed fresh from the oven for optimal crispness.
- Refrigeration: Store any leftover tart, loosely covered, in the refrigerator for up to 2-3 days. The pastry may lose some of its crispness.
- Reheating: Reheat individual slices in a preheated oven or toaster oven at 350°F (175°C) until warmed through and the pastry crisps up again. Avoid microwaving, as it will make the pastry soggy.
- Freezing: While possible, freezing may cause the puff pastry to become less flaky upon thawing. If freezing, wrap cooled slices tightly in plastic wrap then foil for up to 1 month. Reheat from frozen in a low oven or toaster oven until warmed through.
Final Thoughts
This French Onion and Mushroom Tart with Gruyere Cheese is a truly delightful and elegant dish that brings classic French flavors to your table with minimal effort. Its flaky pastry, sweet caramelized onions, earthy mushrooms, and nutty Gruyère combine to create a showstopping savory bake that’s perfect for any occasion. Get ready to impress and savor every delicious bite!
What are your favorite savory tart fillings, or do you have a secret for perfectly caramelized onions? Share your ideas and tips in the comments below, and don’t forget to follow Chefmaniac for more exciting and delicious recipes!
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