A savory, flaky puff pastry tart layered with deeply caramelized onions, creamy Gorgonzola, and rich Brie cheese. This elegant dish makes a perfect appetizer or light meal, bringing a balance of sweet, tangy, and buttery flavors that delight every bite.

Why You’ll Love This Recipe

This caramelized onion tart is irresistible for several reasons:

• It combines the sweetness of slow-cooked onions with the tang of balsamic vinegar and the richness of two creamy cheeses.
• The puff pastry bakes into a light, crisp base that contrasts beautifully with the gooey toppings.
• It’s simple to prepare yet looks and tastes like something from a fine restaurant—ideal for dinner parties or special gatherings.
• The recipe can be served warm or at room temperature, making it convenient for entertaining.
• You can easily adapt it with different herbs or cheeses to suit your taste.

Ingredients

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

• 2 tablespoons extra virgin olive oil
• 4 cups onions, sliced into 1/4-inch thick pieces (about 2 to 3 medium onions)
• 1 tablespoon brown sugar
• 2 tablespoons balsamic vinegar
• 1/2 teaspoon salt
• 1/2 teaspoon black pepper
• 8 ounces (1 sheet) frozen puff pastry, thawed in the refrigerator
• 2 ounces chilled Brie cheese, rind removed and diced
• 2 ounces Gorgonzola or other blue cheese, diced
• 2 tablespoons chopped fresh tarragon (or 1/2 teaspoon crushed fennel seeds as an alternative)

Directions

1. Caramelize the onions:
   Heat olive oil in a large pan over medium-high heat. Add sliced onions and cook for about 10 minutes until they soften and start to brown. Sprinkle in the brown sugar, balsamic vinegar, salt, and pepper. Reduce the heat and cook uncovered for 20–25 minutes, stirring occasionally, until the onions are deeply caramelized. Add a tablespoon of water if they start to dry out. Allow the onions to cool slightly.
2. Prepare the puff pastry:
   Preheat your oven to 400°F (200°C). Roll the puff pastry into a rectangle about 10 by 14 inches (or your preferred shape). Place it on a parchment-lined baking sheet. Prick the pastry all over with a fork to prevent large air pockets from forming during baking.
3. Assemble the tart:
   Spread the cooled caramelized onions evenly over the pastry, leaving a small border at the edges. Scatter the diced Brie and Gorgonzola on top. Sprinkle with chopped tarragon.
4. Bake the tart:
   Bake for 18–20 minutes, or until the pastry is puffed and golden and the cheeses are melted.
5. Cool and serve:
   Let the tart rest for 5 minutes before slicing it into squares or wedges. Serve warm or at room temperature.

Servings and Timing

• Servings: 9 to 12 pieces
• Prep Time: 10 minutes
• Cook Time: 50 minutes
• Total Time: 1 hour

Variations

• Cheese Swap: Try goat cheese or feta for a milder flavor, or use a blend of mozzarella and Gruyère for a creamier result.
• Herb Options: Substitute tarragon with thyme, rosemary, or parsley for a different herbal note.
• Vegetable Add-ins: Add thinly sliced mushrooms, roasted red peppers, or spinach for extra texture and flavor.
• Mini Tarts: Cut the puff pastry into smaller squares before baking to create bite-sized appetizers.
• Sweet Twist: Add a drizzle of honey or fig jam before serving for a touch of sweetness.

Storage/Reheating

• Refrigeration: Store leftovers in an airtight container in the refrigerator for up to 3 days.
• Reheating: Warm slices in a preheated oven at 350°F (175°C) for 8–10 minutes to crisp the pastry again. Avoid microwaving, as it can make the crust soggy.
• Freezing: You can freeze the baked tart for up to 1 month. Reheat from frozen in the oven until warmed through.

FAQs

1. Can I make this tart ahead of time?

Yes, you can prepare the caramelized onions a day in advance and assemble the tart just before baking.

2. What type of onions work best?

Yellow or sweet onions are ideal for caramelizing, as they develop a deep, rich sweetness when cooked slowly.

3. Can I use homemade puff pastry?

Absolutely. Homemade puff pastry will make the tart even flakier and richer in flavor.

4. Is there a substitute for Gorgonzola?

Yes, you can use any blue cheese or even goat cheese if you prefer a milder taste.

5. How do I prevent the puff pastry from getting soggy?

Make sure the onions are well-cooked and not watery before spreading them on the pastry.

6. Can I make this tart without tarragon?

Yes, use thyme, rosemary, or parsley instead for a different herbal flavor.

7. What can I serve with this tart?

It pairs beautifully with a simple green salad, roasted vegetables, or a light soup.

8. Can I serve this cold?

Yes, it tastes great at room temperature or even slightly chilled, making it versatile for parties.

9. Can I make it vegetarian-friendly?

This recipe is already vegetarian-friendly as long as your cheese choices are suitable for vegetarians.

10. How do I know when the tart is done baking?

The puff pastry should be golden and crisp, and the cheese should be bubbling and lightly browned.

Conclusion

This Caramelized Onion Tart with Gorgonzola and Brie is the perfect balance of simplicity and sophistication. With its buttery crust, sweet-savory onions, and creamy cheeses, it’s sure to impress guests or elevate a cozy dinner at home. Serve it as a starter, a side, or even the main attraction—it’s a dish that always delights.

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