Golden Caramelized Onion & Gruyère Puff Pastry Tart Recipe

Introduction

This Golden Caramelized Onion & Gruyère Puff Pastry Tart is a perfect blend of sweet, savory, and cheesy flavors. Its flaky puff pastry base paired with rich caramelized onions and nutty Gruyère makes it an elegant appetizer or a satisfying 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.
3. Step 3: Cook slowly, stirring often, for 25–30 minutes, until onions are golden brown and jammy.
4. Step 4: Stir in thyme and set aside to cool slightly.
5. Step 5: Preheat oven to 400°F (200°C).
6. Step 6: Place puff pastry on a parchment-lined baking sheet.
7. Step 7: Score a 1-inch border around the edges without cutting through the pastry.
8. Step 8: Lightly prick the inner section with a fork to prevent puffing too much.
9. Step 9: Brush edges with beaten egg and bake for 10 minutes, until lightly golden.
10. Step 10: In a bowl, whisk together cream, egg, pepper, and Gruyère cheese.
11. Step 11: Spread Dijon mustard (if using) over the pre-baked pastry base.
12. Step 12: Pour the cheese mixture evenly within the scored border.
13. Step 13: Top generously with caramelized onions.
14. Step 14: Return to oven and bake for 15–18 minutes, until the tart is puffed and golden brown.
15. Step 15: Sprinkle with fresh thyme and a touch of sea salt.
16. Step 16: Slice into squares and serve warm or at room temperature.

Tips & Variations

• For a deeper onion flavor, caramelize the onions slowly over low heat and avoid rushing the process.
• Swap Gruyère for Comté or aged cheddar if preferred.
• Adding a pinch of nutmeg to the cheese mixture enhances the flavor complexity.
• If you like a bit of heat, sprinkle red pepper flakes on top before baking.

Storage

Store leftover tart in an airtight container in the refrigerator for up to 3 days. Reheat gently in a 350°F (175°C) oven for 8–10 minutes to retain crispness. This tart is best enjoyed fresh but can also be served cold.

How to Serve

Serve this delicious recipe with your favorite sides.

FAQs

Can I use frozen puff pastry directly from the freezer?

It’s best to thaw puff pastry completely according to package instructions before using to ensure even baking and proper puffing.

Can I prepare the caramelized onions in advance?

Yes, caramelized onions can be made a day ahead and stored in the refrigerator. Reheat gently before assembling the tart.

Golden Caramelized Onion & Gruyère Puff Pastry Tart Recipe

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★★★★★

4.4 from 105 reviews

This Golden Caramelized Onion & Gruyère Puff Pastry Tart is a deliciously savory treat perfect for brunch, appetizers, or a light meal. Featuring sweet, slow-cooked onions paired with nutty Gruyère cheese atop a crisp, buttery puff pastry, this tart balances rich flavors and flaky textures beautifully. A hint of thyme and optional Dijon mustard add depth, making it an elegant yet easy-to-make dish.

• Author: Naya
• Prep Time: 15 minutes
• Cook Time: 40 minutes
• Total Time: 55 minutes
• Yield: 6 servings 1x
• Category: Appetizer
• Method: Baking
• Cuisine: French

Ingredients

Scale 1x2x3x

Pastry Base

• 1 sheet puff pastry, thawed (about 10×10 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 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 frequently, for 25–30 minutes until the onions become golden brown and jammy. Stir in fresh thyme leaves and set the mixture aside to cool slightly.
2. Preheat Oven and Prepare Pastry: Preheat your oven to 400°F (200°C). Place the thawed puff pastry sheet on a parchment-lined baking sheet. Using a knife, score a 1-inch border around the edges without cutting through. Lightly prick the inner area with a fork to prevent excessive puffing during baking.
3. Blind Bake Pastry Base: Brush the edges of the puff pastry with beaten egg. Bake the pastry for 10 minutes until it turns lightly golden.
4. Prepare Cheese Mixture: In a bowl, whisk together the heavy cream, egg, black pepper, and shredded Gruyère cheese until well combined.
5. Assemble Tart: If using, spread Dijon mustard evenly over the pre-baked pastry base within the scored border. Pour the cheese mixture over the mustard layer evenly. Top generously with the caramelized onions on the cheese mixture.
6. Bake Tart: Return the tart to the oven and bake for 15–18 minutes until the pastry is puffed and golden brown and the cheese filling is set.
7. Garnish and Serve: Once baked, sprinkle fresh thyme leaves and a pinch of sea salt over the tart. Slice into squares and serve warm or at room temperature for best flavor.

Notes

• Caramelizing onions requires patience; cook them slowly to develop deep, rich flavor.
• The Dijon mustard is optional but adds a nice tangy depth to the tart.
• Ensure the puff pastry is fully thawed before scoring and baking to avoid cracking.
• Let the tart cool slightly before slicing to keep the cheese filling intact.
• This tart can be served warm or at room temperature, making it great for entertaining.

Keywords: caramelized onion tart, Gruyère puff pastry tart, savory tart, French tart, caramelized onions, puff pastry recipe, appetizer recipes, easy baked tart