Caramelized Onion Tart with Gruyere and Thyme

Introduction

When I first tried making this Caramelized Onion Tart with Gruyere and Thyme, it instantly became a favorite in my household. The combination of sweet, deeply caramelized onions, rich Gruyere cheese, and aromatic thyme encased in a buttery, flaky pie crust is simply irresistible. My family couldn’t stop raving about it, and it quickly became a staple for weekend dinners, holidays, and even as an elegant appetizer for guests. The balance of savory and sweet flavors, along with the depth of caramelized onions, makes this tart a showstopper every time. If you’re looking for a dish that feels both indulgent and sophisticated, this caramelized onion tart is definitely worth a try!

Why You’ll Love This Caramelized Onion Tart with Gruyere and Thyme

There’s something magical about the pairing of caramelized onions and Gruyere cheese. The onions, once sweet and tender after slow cooking, meld perfectly with the nutty and slightly sharp flavor of Gruyere. The addition of balsamic vinegar and fresh thyme takes it a step further by adding a depth of flavor and an herby fragrance that elevates the dish. Whether you’re serving it as a main course, a side, or an appetizer, this tart is guaranteed to impress. Plus, it’s incredibly easy to make with only a few simple ingredients. The result is a comforting, gourmet dish that will wow both your family and guests.

Ingredients

For the Tart:

• 1 pie crust, preferably homemade (blind baked)
• 4 large onions, sliced into ¼-inch rounds
• 1 tablespoon sugar
• ½ teaspoon kosher salt
• 1½ tablespoons balsamic vinegar
• 2 tablespoons fresh thyme, chopped (or 2 teaspoons dried thyme)
• ¼ teaspoon freshly ground black pepper
• ¼ cup heavy cream
• 1 cup Gruyere cheese, grated

Instructions

Step 1: Blind Bake the Crust

To start, prepare your pie crust. You can use a store-bought crust or make a homemade one. If you choose to make your own crust, I highly recommend following the detailed instructions in Lea Ann Brown’s Pie Crust Article for the perfect flaky base. Once your crust is ready, place it in a tart pan and blind bake it. Blind baking involves partially baking the crust before filling it, ensuring it stays crisp and doesn’t get soggy once the filling is added. Allow the crust to cool before adding the filling.

Step 2: Caramelize the Onions

In a large frying pan, heat the olive oil over medium heat. Add the sliced onions, sugar, and kosher salt. The sugar helps the onions caramelize, giving them a sweet, rich flavor. Stir the onions often, and let them cook for about 30 minutes until they reduce in size by about two-thirds. If the pan seems dry, add a tablespoon of butter to keep the onions from sticking. The onions should be soft and golden by this point.

Next, stir in the balsamic vinegar and lower the heat. Continue cooking for another 15 minutes, stirring frequently. The onions will turn a deep golden brown and become fully caramelized. This process brings out the natural sweetness in the onions and makes the filling for your tart irresistibly flavorful.

Step 3: Add Flavor

Once the onions are perfectly caramelized, remove the pan from heat and stir in the fresh thyme and black pepper. The thyme adds a fragrant, earthy note that pairs wonderfully with the sweetness of the onions. Allow the mixture to cool slightly before adding the heavy cream. Stir the cream in until the mixture is smooth and fully combined. The cream helps bind the filling and adds a creamy richness.

Step 4: Assemble the Tart

Preheat the oven to 350°F (175°C). Take your cooled, blind-baked pie crust and spread the caramelized onion mixture evenly into the tart shell. Make sure to distribute the onions well to ensure every bite is flavorful. Once the onions are in place, sprinkle the grated Gruyere cheese evenly over the top. The cheese will melt beautifully in the oven, creating a savory, golden layer over the top of the onions.

Step 5: Bake

Place the tart in the preheated oven and bake for about 15 minutes, or until the filling is set, and the cheese has melted and started to brown slightly. The tart should be golden and bubbly, with the cheese creating a lovely crust on top. If you’d like a crispier top, you can broil it for an additional minute, but be careful not to burn the cheese.

Step 6: Serve

Let the tart cool slightly before serving. This allows the flavors to set and makes it easier to slice. Serve the tart warm or at room temperature. For an extra touch of elegance, garnish with fresh thyme sprigs before serving. This tart is delicious on its own or paired with a light salad or soup.

Nutrition Facts (per serving)

• Serving Size: 1 slice (based on 8 servings per tart)
• Calories: 300 kcal
• Sugar: 8g
• Sodium: 450mg
• Fat: 22g
• Saturated Fat: 10g
• Unsaturated Fat: 9g
• Trans Fat: 0g
• Carbohydrates: 24g
• Fiber: 2g
• Protein: 6g
• Cholesterol: 40mg

Note: Nutritional values are approximate and may vary based on specific ingredients used.

Preparation Time

• Prep Time: 20 minutes
• Cook Time: 60 minutes
• Total Time: 1 hour 20 minutes

How to Serve

• Warm or at room temperature – it tastes great both ways.
• Garnished with fresh thyme sprigs for a fragrant touch.
• Pair with a side salad for a light lunch or dinner.
• Serve as an appetizer during parties or holiday gatherings.
• Top with a dollop of crème fraîche for extra indulgence.

Additional Tips

1. Make it ahead: You can prepare the caramelized onions a day before and refrigerate them. Simply assemble and bake the tart the next day.
2. Use a store-bought crust: If you’re short on time, store-bought pie crust works perfectly fine for this recipe.
3. Add a touch of sweetness: For a richer flavor, add a spoonful of honey or brown sugar while caramelizing the onions.
4. Herb variations: While thyme is ideal, rosemary can also be added for a different flavor profile.
5. Freezing: This tart freezes well, so make extra for later! Just bake and cool it, then wrap and freeze.

FAQ Section

1. Can I use a different type of cheese?
   Yes! While Gruyere adds a lovely nutty flavor, you can substitute it with Swiss cheese, cheddar, or even a tangy blue cheese for a different twist.
2. Can I make this tart without balsamic vinegar?
   Yes, if you prefer a milder flavor, you can omit the balsamic vinegar and simply caramelize the onions with sugar and salt.
3. Can I make the crust from scratch?
   Absolutely! Making your own pie crust adds a homemade touch, and it’s worth the effort for a buttery, flaky base.
4. How can I make this tart vegetarian?
   This recipe is already vegetarian, but you could add some roasted vegetables like mushrooms or bell peppers for added texture and flavor.
5. Can I make this tart in advance?
   Yes, you can prepare the tart up to 24 hours ahead. Simply assemble the tart and store it in the refrigerator until you’re ready to bake it.
6. How do I store leftovers?
   Leftovers can be stored in the refrigerator for up to 3 days. Reheat the tart in the oven for a few minutes before serving.
7. Can I freeze the tart?
   Yes, this tart freezes well. After baking, allow it to cool completely before wrapping it tightly in plastic wrap and foil.
8. How can I make the crust extra flaky?
   Use cold butter and ice water when making your pie crust, and be sure not to overwork the dough.
9. Can I make this recipe gluten-free?
   Yes, you can substitute the pie crust with a gluten-free version. Just ensure your crust choice works well for blind baking.
10. What can I serve this tart with?
    This tart pairs beautifully with a fresh salad, soup, or even a charcuterie board for a delightful appetizer.

Conclusion

The Caramelized Onion Tart with Gruyere and Thyme is a decadent, yet simple dish that combines savory, sweet, and rich flavors in every bite. Whether you’re preparing it for a special occasion or just to enjoy on a weekend evening, it’s guaranteed to be a crowd-pleaser. With its flaky crust, caramelized onions, and creamy Gruyere, this tart is the perfect dish to impress your guests or treat yourself. Don’t hesitate to give it a try, and enjoy the incredible flavors that this recipe brings to your table.

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