Caramelized Onion and Gruyere Tart

Why You’ll Love This Recipe

Caramelized Onion and Gruyere Tart is a delightful balance of flavors and textures. The onions are slowly caramelized to bring out their natural sweetness, while the Gruyere cheese adds a rich, tangy depth. The crisp, buttery pastry crust provides a perfect contrast to the smooth filling, creating a bite that’s both savory and satisfying. This tart is versatile enough to be served warm or at room temperature and pairs well with a simple green salad or roasted vegetables.

Ingredients

• For the Tart Crust:

  • 1 1/4 cups (150g) all-purpose flour

  • 1/4 teaspoon salt

  • 1/2 cup (115g) unsalted butter, cold and cut into cubes

  • 2-3 tablespoons ice water

• For the Filling:

  • 2 tablespoons unsalted butter

  • 3 medium onions, thinly sliced

  • 1 teaspoon sugar (optional, to enhance caramelization)

  • Salt and freshly ground black pepper, to taste

  • 1 teaspoon fresh thyme leaves (or 1/2 teaspoon dried thyme)

  • 1/2 cup (120ml) heavy cream

  • 1 large egg

  • 1 cup (100g) Gruyere cheese, grated

  • 1/4 cup (25g) Parmesan cheese, grated (optional, for added flavor)

(Tip: You’ll find the full list of ingredients and measurements in the recipe card below.)

Directions

For the Tart Crust:

1. Prepare the crust:

   • In a food processor, combine the flour and salt. Add the cold cubed butter and pulse until the mixture resembles coarse crumbs.

   • Gradually add the ice water, one tablespoon at a time, and pulse until the dough just comes together. You may need a bit more water depending on the humidity, but be careful not to overwork the dough.

   • Turn the dough out onto a lightly floured surface and knead it a few times to bring it together. Shape it into a disc, wrap it in plastic wrap, and refrigerate for at least 30 minutes to chill.

2. Roll out the dough:

   • Preheat the oven to 375°F (190°C). On a lightly floured surface, roll out the chilled dough to fit into a 9-inch tart pan. Press the dough gently into the pan, trimming any excess from the edges.

   • Prick the bottom of the crust with a fork and place parchment paper over the dough. Fill with pie weights or dried beans and bake for 10-12 minutes. Remove the weights and parchment and bake for another 5-7 minutes until golden. Set aside to cool.

For the Filling:

3. Caramelize the onions:

   • In a large skillet, melt the butter over medium-low heat. Add the sliced onions and a pinch of salt. Cook slowly for 25-30 minutes, stirring occasionally, until the onions are golden brown and caramelized. You can sprinkle in the sugar halfway through to help with caramelization.

   • Add the thyme and cook for another 2 minutes. Remove from heat and let the onions cool slightly.

4. Prepare the filling:

   • In a medium bowl, whisk together the heavy cream and egg until smooth. Stir in the grated Gruyere cheese and Parmesan cheese (if using). Season with salt and pepper to taste.

5. Assemble the tart:

   • Spread the caramelized onions evenly over the baked tart crust.

   • Pour the cream and cheese mixture over the onions, ensuring everything is evenly coated.

6. Bake the tart:

   • Bake in the preheated oven for 25-30 minutes, or until the filling is set and golden on top. The edges should be slightly browned, and the center should be firm to the touch.

7. Serve:

   • Let the tart cool slightly before slicing. Garnish with extra thyme or fresh herbs, if desired. Serve warm or at room temperature with a side salad or roasted vegetables.

Servings and Timing

• Servings: 6-8

• Prep time: 30 minutes (plus chilling time for the dough)

• Cook time: 60 minutes

• Total time: 1 hour 30 minutes

Variations

• Vegetarian Option: This tart is already vegetarian, but you can add sautéed mushrooms, spinach, or roasted bell peppers for extra flavor and color.

• Herb Variations: Try using rosemary, sage, or basil instead of thyme for a different flavor profile.

• Gluten-Free: Use a gluten-free tart crust to make this dish gluten-free. There are many store-bought options, or you can make your own with a gluten-free flour blend.

Storage/Reheating

• Storage: Store any leftover tart in an airtight container in the refrigerator for up to 3 days.

• Reheating: Reheat in the oven at 350°F (175°C) for 10-15 minutes until warmed through and the crust is crispy again.

• Freezing: You can freeze the baked tart for up to 1 month. Wrap it tightly in plastic wrap and aluminum foil, then thaw in the refrigerator overnight and reheat in the oven.

FAQs

Can I use a different cheese in place of Gruyere?

Yes, you can substitute Gruyere with Swiss cheese, fontina, or even a mild cheddar for a different flavor. Gruyere has a distinctive nutty flavor, but these cheeses can still work well.

Can I make the crust ahead of time?

Yes, you can prepare the crust ahead of time and refrigerate it for up to 2 days. Alternatively, you can freeze the unbaked crust for up to 2 months and bake it when you’re ready.

Can I use store-bought puff pastry instead of making the crust?

Yes, you can use store-bought puff pastry as a shortcut. Just roll it out to fit your tart pan and bake according to package instructions.

How do I prevent the crust from becoming soggy?

Baking the crust blind (pre-baking with pie weights) helps ensure it stays crisp. You can also brush the crust with a thin layer of egg wash (beaten egg) before filling to create a barrier.

Can I serve this tart cold?

Yes, this tart can be served cold or at room temperature, which makes it perfect for picnics, potlucks, or make-ahead meals.

Conclusion

Caramelized Onion and Gruyere Tart is a delightful dish that’s full of rich, savory flavors and a buttery, flaky crust. It’s perfect for any occasion, whether it’s a casual meal or a festive gathering. The combination of sweet caramelized onions and nutty Gruyere cheese creates a mouthwatering experience that will leave you craving more. Enjoy this easy-to-make tart with a fresh salad, and it’s sure to become a new favorite in your recipe collection!

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