Golden Caramelized Onion & Gruyère Puff Pastry Tart Recipe

Introduction

This Golden Caramelized Onion & Gruyère Puff Pastry Tart offers a perfect balance of sweet, savory, and cheesy flavors. With slowly caramelized onions, rich Gruyère cheese, and a flaky puff pastry crust, it’s a crowd-pleasing appetizer or light meal.

Ingredients

• 1 sheet puff pastry, thawed (about 10×10 inches)
• 1 egg, beaten (for brushing)
• 1 tbsp Dijon mustard (optional, for flavor depth)
• 3 large yellow onions, thinly sliced
• 2 tbsp butter
• 1 tbsp olive oil
• 1 tsp sugar
• Salt, to taste
• 1 tsp fresh thyme leaves (plus more for garnish)
• 1 cup (100 g) shredded Gruyère cheese
• ¼ cup (60 ml) heavy cream
• 1 egg
• ½ tsp black pepper

Instructions

1. Step 1: In a large skillet, melt butter with olive oil over medium heat.
2. Step 2: Add sliced onions, sugar, and a pinch of salt. Cook slowly, stirring often, for 25–30 minutes until the onions are golden brown and jammy.
3. Step 3: Stir in thyme and set the onions aside to cool slightly.
4. Step 4: Preheat the oven to 400°F (200°C).
5. Step 5: Place the puff pastry on a parchment-lined baking sheet. Score a 1-inch border around the edges without cutting through.
6. Step 6: Lightly prick the inner section with a fork to prevent excessive puffing.
7. Step 7: Brush the edges with the beaten egg and bake for 10 minutes until lightly golden.
8. Step 8: In a bowl, whisk together cream, egg, black pepper, and Gruyère cheese.
9. Step 9: Spread Dijon mustard (if using) over the pre-baked pastry base.
10. Step 10: Pour the cheese mixture evenly within the scored border, then top generously with the caramelized onions.
11. Step 11: Return to the oven and bake for 15–18 minutes until the tart is puffed and golden brown.
12. Step 12: Sprinkle with fresh thyme and a touch of sea salt. Slice into squares and serve warm or at room temperature.

Tips & Variations

• For a deeper onion flavor, cook the onions even longer on very low heat, stirring occasionally.
• Use vegetarian-friendly Dijon mustard to keep the tart vegetarian.
• Add a sprinkle of nutmeg to the cheese mixture for a warm, subtle spice.
• Serve with a crisp green salad for a light meal.

Storage

Store leftovers in an airtight container in the refrigerator for up to 2 days. Reheat gently in a low oven (about 300°F/150°C) for 10 minutes to restore crispness. This tart is best enjoyed fresh but can also be served cold or at room temperature.

How to Serve

Serve this delicious recipe with your favorite sides.

FAQs

Can I use other types of cheese instead of Gruyère?

Yes, Swiss, Emmental, or a mild cheddar can be good alternatives, though Gruyère’s nutty flavor is ideal for this tart.

Do I have to use Dijon mustard?

Dijon mustard adds a nice tang and depth but is optional. You can skip it or substitute with a mild mustard of your choice.

Golden Caramelized Onion & Gruyère Puff Pastry Tart Recipe

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★★★★★

4.8 from 130 reviews

This Golden Caramelized Onion & Gruyère Puff Pastry Tart is a delicious French-inspired appetizer featuring sweet, jammy caramelized onions paired with nutty Gruyère cheese atop a flaky puff pastry crust. Perfectly baked to a golden brown, this tart offers a harmonious blend of savory flavors and buttery textures, making it an ideal dish for entertaining or a satisfying snack.

• Author: Clara
• Prep Time: 15 minutes
• Cook Time: 45 minutes
• Total Time: 60 minutes
• Yield: 6 servings 1x
• Category: Appetizer
• Method: Baking
• Cuisine: French
• Diet: Vegetarian

Ingredients

Scale 1x2x3x

Puff Pastry Base

• 1 sheet puff pastry, thawed (about 10x10 inches)
• 1 egg, beaten (for brushing)
• 1 tbsp Dijon mustard (optional, for flavor depth)

Caramelized Onions

• 3 large yellow onions, thinly sliced
• 2 tbsp butter
• 1 tbsp olive oil
• 1 tsp sugar
• Salt, to taste
• 1 tsp fresh thyme leaves (plus more for garnish)

Cheese Mixture

• 1 cup (100 g) shredded Gruyère cheese
• ¼ cup (60 ml) heavy cream
• 1 egg
• ½ tsp black pepper

Instructions

1. Caramelize the Onions: In a large skillet, melt butter with olive oil over medium heat. Add the thinly sliced onions, sugar, and a pinch of salt. Cook slowly, stirring often, for 25–30 minutes until the onions become golden brown and jammy, then stir in the fresh thyme leaves. Set aside to cool slightly.
2. Prepare the Oven and Pastry: Preheat your oven to 400°F (200°C). Place the thawed puff pastry sheet onto a parchment-lined baking sheet. Using a knife, score a 1-inch border around the edges carefully without cutting through the dough. Lightly prick the inner section with a fork to prevent excessive puffing during baking. Brush the edges with the beaten egg to enhance browning.
3. Pre-Bake the Pastry: Bake the prepared puff pastry in the preheated oven for about 10 minutes or until the edges turn lightly golden. This step ensures a crisp crust that can hold the toppings.
4. Make the Cheese Mixture: In a mixing bowl, whisk together the heavy cream, egg, black pepper, and shredded Gruyère cheese until fully combined.
5. Assemble the Tart: If using, spread the Dijon mustard evenly over the pre-baked pastry base within the scored border. Pour the cheese mixture on top, spreading it evenly inside the border. Then, generously layer the caramelized onions over the cheese mixture.
6. Final Bake: Return the tart to the oven and bake for an additional 15–18 minutes, or until the tart is puffed up and golden brown.
7. Garnish and Serve: Remove from the oven and sprinkle fresh thyme leaves and a pinch of sea salt over the tart. Slice into squares and serve warm or at room temperature for the best flavor.

Notes

• For a vegetarian option, ensure the Dijon mustard used is vegetarian-friendly.
• This tart can be served as an elegant appetizer or a main dish when paired with a fresh salad.
• To enhance the flavor, use high-quality Gruyère cheese and fresh thyme.
• Allow the tart to cool slightly before slicing to prevent the filling from spilling.

Keywords: caramelized onion tart, Gruyère cheese tart, puff pastry tart, French appetizer, baked cheese tart, savory tart recipe