Caramelized Onion Tart With Puff Pastry

Why You’ll Love This Recipe

I love how this tart combines flaky pastry with soft, sweet onions and creamy, savory cheese. Slowly caramelizing the onions takes a little patience, but I find that their rich flavor makes the extra cooking time worthwhile.

I also like that store-bought puff pastry does most of the work for me. I can caramelize the onions ahead of time, assemble the tart when I need it, and easily change the cheese or herbs to create different versions.

Ingredients

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

• Puff pastry – I use one thawed sheet as the flaky, buttery base of my tart.
• Yellow onions – I thinly slice the onions so they cook evenly and caramelize beautifully.
• Butter – I use butter to give the onions a rich flavor.
• Olive oil – I combine it with the butter to help cook the onions gently.
• Brown sugar – I add a small amount to complement the onions’ natural sweetness.
• Balsamic vinegar – I use a splash to balance the sweetness and add depth.
• Goat cheese – I like its creamy texture and tangy flavor with caramelized onions.
• Fresh thyme – I use thyme for a fresh, earthy flavor.
• Salt – I add salt to season the onions and help bring out their natural flavor.
• Black pepper – I use freshly ground black pepper for a little extra savory flavor.
• Egg – I beat an egg with a splash of water to make an egg wash for the pastry edges.

Directions

1. I heat the butter and olive oil in a large skillet over medium-low heat. Once the butter has melted, I add the sliced onions and a pinch of salt.
2. I cook the onions slowly for about 30–40 minutes, stirring occasionally. I keep the heat relatively low so the onions soften and turn deep golden brown instead of burning.
3. Once the onions are caramelized, I stir in the brown sugar and balsamic vinegar. I cook the mixture for another 2–3 minutes, then remove it from the heat and allow it to cool slightly.
4. I preheat my oven to 400°F (200°C) and line a large baking sheet with parchment paper.
5. I place the thawed puff pastry on the prepared baking sheet. Using a sharp knife, I lightly score a border about 1 inch from the edges without cutting completely through the pastry.
6. I prick the center of the pastry several times with a fork. This helps control how much the center rises while leaving the edges free to puff.
7. I crumble or spread the goat cheese over the center of the pastry, staying inside the scored border.
8. I spread the cooled caramelized onions evenly over the cheese and sprinkle fresh thyme and black pepper over the top.
9. I brush the exposed pastry border with the beaten egg wash.
10. I bake the tart for approximately 20–25 minutes, or until the pastry is puffed, crisp, and deeply golden around the edges.
11. I let the tart rest for about 5–10 minutes before slicing. I like adding a few fresh thyme leaves just before serving.

Servings and Timing

I usually cut this tart into smaller pieces when serving it as an appetizer or larger slices when serving it for lunch or brunch.

• Prep time: 15 minutes
• Caramelizing time: 30–40 minutes
• Baking time: 20–25 minutes
• Total time: About 1 hour 10 minutes
• Servings: About 6–8 appetizer servings or 4 larger servings

Variations

For a Gruyère version, I replace the goat cheese with shredded Gruyère. I love how its nutty, savory flavor complements the sweet onions.

When I want something milder and creamier, I use ricotta or cream cheese. Brie is another option I enjoy when I want an especially rich tart.

For extra sweetness, I sometimes arrange thin pear or apple slices underneath the caramelized onions. I can also drizzle a little honey over the finished tart.

When I want more texture, I scatter chopped walnuts or pecans over the tart before serving. I also like replacing the thyme with rosemary when I want a stronger herbal flavor.

Storage/Reheating

I store leftover caramelized onion tart in an airtight container in the refrigerator for up to 3 days. If I am storing several pieces together, I place parchment paper between the layers to help prevent sticking.

To reheat the tart, I place it on a baking sheet in a 350°F (175°C) oven for approximately 8–12 minutes. I can also use an air fryer for a few minutes. I avoid using the microwave when possible because it tends to make my puff pastry soft instead of crisp.

For advance preparation, I caramelize the onions up to 4 days ahead and keep them refrigerated in an airtight container. I then assemble and bake the tart when I am ready to serve it.

FAQs

Can I make Caramelized Onion Tart With Puff Pastry ahead of time?

I prefer baking the tart shortly before serving so the puff pastry stays crisp. However, I can caramelize my onions several days in advance and refrigerate them, which significantly reduces the preparation time on the day I make the tart.

How do I stop the puff pastry from getting soggy?

I make sure my caramelized onions are not overly wet and allow them to cool before adding them to the pastry. I also avoid overloading the tart with toppings and bake it until the bottom and edges are properly golden and crisp.

What cheese goes best with caramelized onions?

I particularly like goat cheese because its tanginess balances the sweetness of the onions. Gruyère, Brie, feta, ricotta, cream cheese, and blue cheese are other options I can use depending on the flavor I want.

Can I use red onions instead of yellow onions?

Yes. I can use red onions, although they produce a slightly different flavor and appearance. I generally prefer yellow onions because their natural sweetness develops particularly well during slow caramelization.

Can I serve caramelized onion tart cold?

I can serve the tart at room temperature, which makes it convenient for parties and brunches. However, I think the texture is best when the tart is served warm or slightly warm because the pastry remains crisp and the cheese is soft.

Conclusion

This Caramelized Onion Tart With Puff Pastry is a recipe I love for its combination of simplicity and rich flavor. The crisp, buttery pastry provides the perfect base for sweet caramelized onions, creamy cheese, and fragrant thyme.

Caramelized Onion Tart With Puff Pastry

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A crisp, golden puff pastry tart layered with creamy goat cheese, deeply caramelized onions, and fresh thyme. This elegant savory tart is perfect for appetizers, brunch, lunch, or holiday entertaining.

• Author: Laura
• Prep Time: 15 minutes
• Cook Time: 55 minutes
• Total Time: 1 hour 10 minutes
• Yield: 6–8 appetizer servings or 4 larger servings
• Category: Appetizer
• Method: Baking
• Cuisine: French-Inspired
• Diet: Vegetarian

Ingredients

• 1 sheet puff pastry, thawed
• Yellow onions, thinly sliced
• Butter
• Olive oil
• Brown sugar
• Balsamic vinegar
• Goat cheese, crumbled or softened
• Fresh thyme
• Salt
• Freshly ground black pepper
• 1 egg, beaten with a splash of water

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Instructions

1. Heat the butter and olive oil in a large skillet over medium-low heat. Add the sliced onions and a pinch of salt.
2. Cook the onions for 30–40 minutes, stirring occasionally, until soft and deeply golden brown.
3. Stir in the brown sugar and balsamic vinegar. Cook for another 2–3 minutes, then remove from the heat and allow the onions to cool slightly.
4. Preheat the oven to 400°F (200°C) and line a large baking sheet with parchment paper.
5. Place the thawed puff pastry on the prepared baking sheet. Lightly score a 1-inch border around the edges without cutting completely through the pastry.
6. Prick the center of the pastry several times with a fork, leaving the scored border untouched.
7. Spread or crumble the goat cheese over the center of the pastry, keeping it inside the scored border.
8. Spread the cooled caramelized onions evenly over the cheese. Sprinkle with fresh thyme and black pepper.
9. Brush the exposed pastry border with the egg wash.
10. Bake for 20–25 minutes, or until the pastry is puffed, crisp, and deeply golden around the edges.
11. Allow the tart to rest for 5–10 minutes before slicing. Garnish with additional fresh thyme if desired and serve warm or at room temperature.

Notes

• Gruyère, Brie, feta, ricotta, cream cheese, or blue cheese can be substituted for the goat cheese.
• For a sweet-savory variation, add thin pear or apple slices beneath the caramelized onions or drizzle the finished tart with honey.
• Chopped walnuts or pecans can be added for extra texture, and rosemary can replace the thyme.
• Allow the caramelized onions to cool and avoid overly wet toppings to help keep the puff pastry crisp.
• Store leftovers in an airtight container in the refrigerator for up to 3 days. Reheat at 350°F (175°C) for 8–12 minutes or briefly in an air fryer.
• The onions can be caramelized up to 4 days ahead and refrigerated in an airtight container until ready to assemble the tart.

Nutrition

• Serving Size: 1 of 8 appetizer servings
• Calories: 280 kcal
• Sugar: 6 g
• Sodium: 260 mg
• Fat: 19 g
• Saturated Fat: 8 g
• Unsaturated Fat: 10 g
• Trans Fat: 0 g
• Carbohydrates: 23 g
• Fiber: 2 g
• Protein: 6 g
• Cholesterol: 35 mg