Mediterranean French Onion & Mushroom Tart with Gruyère
This Mediterranean French Onion & Mushroom Tart is a show-stopping savory pastry that’s both rustic and refined. Featuring deeply caramelized onions, sautéed mushrooms, earthy herbs, and nutty Gruyère cheese, all nestled in a buttery tart shell—this dish brings together French comfort and Mediterranean charm.
Whether served as a brunch centerpiece, elegant appetizer, or a light vegetarian dinner with salad, it’s packed with umami, sophistication, and melt-in-your-mouth flavor in every bite.
Time
Prep Time: 25 minutes
Cook Time: 45 minutes
Chill Time (for pastry): 30 minutes (optional, if using homemade dough)
Total Time: ~1 hour 10 minutes
Servings: 6–8 slices
Ingredients
For the Tart Crust (or use store-bought shortcrust/puff pastry):
1¼ cups (160g) all-purpose flour
½ tsp salt
100g (7 tbsp) cold unsalted butter, cubed
3–4 tbsp ice water
For the Caramelized Onion & Mushroom Filling:
2 tbsp olive oil
1 tbsp unsalted butter
2 large yellow onions, thinly sliced
2 cloves garlic, minced
200g (7 oz) cremini or button mushrooms, sliced
1 tsp balsamic vinegar or white wine
½ tsp dried thyme (or 1 tsp fresh)
½ tsp dried oregano
Salt & black pepper to taste
For the Creamy Base:
½ cup whole milk ricotta or crème fraîche
2 large eggs
1 tsp Dijon mustard (optional)
Salt & pepper, to taste
Cheese & Topping:
1½ cups (150g) grated Gruyère cheese
2 tbsp grated Parmesan (optional)
Fresh parsley or basil, for garnish
Instructions
Step 1: Prepare the Tart Crust (if making from scratch)
In a bowl, combine flour and salt. Cut in cold butter until mixture resembles coarse crumbs.
Add ice water gradually, mixing until dough just holds together.
Form into a disc, wrap in plastic, and chill for 30 minutes.
Roll out to fit a 9-inch tart pan. Press into the pan and trim edges. Prick bottom with a fork.
Prebake the crust at 190°C (375°F) for 10 minutes. Let cool slightly.
Skip this step if using store-bought tart or puff pastry. Prebake store-bought crust as per package instructions.
Step 2: Caramelize the Onions
Heat olive oil and butter in a skillet over medium-low heat.
Add onions and a pinch of salt. Cook slowly, stirring often, for 20–25 minutes until golden and caramelized.
Stir in garlic, thyme, and oregano. Cook for 1–2 minutes more.
Add mushrooms and increase heat to medium-high. Cook until mushrooms are browned and any moisture has evaporated, about 6–8 minutes.
Deglaze with balsamic vinegar or wine and cook for another minute. Season with salt and pepper. Set aside.
Step 3: Prepare the Creamy Base
In a small bowl, whisk together ricotta (or crème fraîche), eggs, Dijon mustard, and a pinch of salt and pepper.
Step 4: Assemble the Tart
Spread the ricotta-egg mixture evenly in the pre-baked crust.
Add the caramelized onion and mushroom mixture.
Sprinkle generously with Gruyère and a little Parmesan if using.
Step 5: Bake
Bake at 190°C (375°F) for 25–30 minutes, or until the cheese is melted, golden, and bubbly.
Let cool slightly before slicing. Garnish with fresh parsley or basil.
Tips for Success
Low and slow is key for perfect caramelized onions. Rushing can lead to browning, not sweetness.
Gruyère melts beautifully and adds a nutty depth—substitute with Emmental or Fontina if needed.
Ricotta or crème fraîche creates a light custard base that complements the rich toppings.
Make ahead: You can prep the onions and mushrooms a day in advance.
Variations
Vegan: Use vegan pastry, caramelize onions in oil only, and use plant-based ricotta and cheese.
With meat: Add thinly sliced prosciutto, cooked pancetta, or shredded rotisserie chicken for added protein.
Herbed twist: Mix chopped sun-dried tomatoes, olives, or roasted red peppers into the mushroom mixture.
Mini tarts: Use muffin tins for individual tartlets—great for parties!
FAQs
Q: Can I freeze this tart?
A: Yes! Once fully baked and cooled, wrap and freeze slices. Reheat in the oven until warm and crisp.
Q: Can I use puff pastry?
A: Absolutely. Puff pastry makes a flakier, lighter crust—just roll out, dock with a fork, and prebake lightly.
Q: Can I make it ahead of time?
A: Yes, it reheats beautifully. You can bake it the day before and reheat in the oven at 170°C (340°F) for 10–15 minutes.
Q: What to serve it with?
A: A side of arugula salad with lemon vinaigrette or a bowl of tomato basil soup pairs beautifully.
Nutrition Information (Per Slice, based on 8 slices)
Calories: 290
Protein: 10g
Fat: 20g
Carbs: 16g
Fiber: 2g
Sugar: 3g
Sodium: 330mg
Calcium: 220mg
(May vary based on crust and cheese brand.)
Conclusion
This Mediterranean French Onion & Mushroom Tart with Gruyère is a soul-warming blend of caramelized sweetness, savory depth, and nutty creaminess. Whether it’s part of your brunch table, a cozy dinner, or a potluck contribution, this tart is sure to impress.
It’s elegant yet easy, and every bite brings the richness of French bistro fare with a Mediterranean twist—simple ingredients, slowly cooked to perfection, wrapped in buttery pastry bliss.