If you’re searching for a show-stopping appetizer or brunch centerpiece, look no further than this Caramelized Onion Tart. Imagine flaky, golden puff pastry piled high with sweet, deeply caramelized onions, finished with a shower of melty Gruyère and a sprinkle of tangy goat cheese. This French-inspired vegetarian tart is pure comfort with a sophisticated twist—a recipe I adore sharing with friends at any gathering.
Ingredients You’ll Need
This Caramelized Onion Tart is all about simple ingredients coming together for something truly special. Each item on the list serves an important purpose, impacting the flavor, texture, and irresistible aroma that will fill your kitchen.
- Puff pastry: The foundation of the tart, puff pastry bakes up crisp and buttery, providing a beautiful contrast to the soft onions.
- Unsalted butter: Adds richness and depth to the caramelized onions, making every bite luscious.
- Olive oil: Prevents the butter from burning and adds an earthy note to the onion filling.
- Yellow onions: The star of the show—choose large, sweet onions for maximum flavor and beautiful caramelization.
- Salt: Essential for drawing out the onions’ moisture and intensifying their sweetness as they cook down.
- Sugar: Just a touch helps speed up caramelization and balances the savory elements.
- Fresh thyme leaves: Offers a fresh, herbaceous lift that pairs perfectly with onions and cheese.
- Gruyère or Swiss cheese: Melts beautifully and lends a nutty, savory backbone to the tart.
- Goat cheese or feta (optional): For a creamy, tangy finish that contrasts the sweet onions—totally optional but highly recommended!
- Egg (for egg wash): Brushed on the pastry border for a gorgeous golden sheen and slight crunch.
- Freshly ground black pepper: Adds a little kick and balances the sweetness of the onions.
How to Make Caramelized Onion Tart
Step 1: Caramelize the Onions
Start by melting the butter with olive oil in a large skillet over medium heat. Add your thinly sliced onions, then sprinkle in the salt and sugar. The trick here is patience—stir occasionally, letting the onions cook down for about 25 to 30 minutes until they’re deep gold and sticky-sweet. Don’t rush this step! The slow caramelization is what gives the Caramelized Onion Tart its signature flavor and gorgeous color. Stir in the thyme and some black pepper at the end for that perfect finishing touch.
Step 2: Prepare the Puff Pastry
While your onions are transforming, roll out the thawed puff pastry on a lightly floured surface. Carefully transfer it to a parchment-lined baking sheet. Using a sharp knife, score a 1/2-inch border around the edge (but don’t cut all the way through), and prick the center with a fork. This helps the edges puff up while the center stays flat—giving you a perfect tart shape. Brush the border with beaten egg for a shiny, golden finish.
Step 3: Assemble the Tart
Spread the glorious caramelized onions evenly within your scored border. Next, sprinkle over the Gruyère, letting it nestle into those onions, then scatter with goat cheese or feta if you’re using it. The cheese will melt and bubble in the oven, creating pockets of creamy, tangy flavor that take this Caramelized Onion Tart to the next level.
Step 4: Bake to Perfection
Slide the tart into your preheated 400°F (200°C) oven. Bake for 20 to 25 minutes, or until the pastry edges are deeply golden and crisp. The cheese should be melted and just starting to take on a little color. Let the tart cool for a few minutes before slicing—this helps everything set up and makes serving a breeze.
How to Serve Caramelized Onion Tart
Garnishes
For a finishing touch, sprinkle a few more fresh thyme leaves over the tart, or add a light drizzle of good olive oil. A crack of black pepper or a dusting of flaky sea salt can make each slice extra special and visually appealing.
Side Dishes
This Caramelized Onion Tart loves company! Serve it with a crisp green salad tossed in a zesty vinaigrette, a bowl of marinated olives, or even a simple tomato salad. These sides refresh your palate and round out the meal beautifully, whether for brunch, lunch, or a light dinner.
Creative Ways to Present
If you’re hosting, try cutting the tart into small squares for finger-friendly appetizers. You can also bake mini tarts using a muffin tin for individual servings—adorable and perfect for parties. For an elegant brunch, pair slices with poached eggs or smoked salmon alongside.
Make Ahead and Storage
Storing Leftovers
Wrap leftover Caramelized Onion Tart slices in foil or store in an airtight container in the fridge. They’ll keep for up to three days, and the flavors just deepen as they sit.
Freezing
Yes, you can freeze this tart! Once cooled, wrap slices tightly in plastic wrap and foil. Store for up to one month. Thaw overnight in the refrigerator before reheating for best results.
Reheating
For the crispiest results, reheat your tart in a 350°F (175°C) oven for about 10 minutes. The pastry will regain its crunch, and the cheese will melt beautifully. Microwaving works in a pinch, but you’ll lose some of that lovely crisp texture.
FAQs
Can I use red onions instead of yellow?
Absolutely! Red onions will add a slightly different flavor and a beautiful color to your Caramelized Onion Tart. They tend to be a bit sweeter, so you may want to reduce the sugar slightly.
Do I need to thaw the puff pastry first?
Yes, for the best texture and ease of handling, let your puff pastry thaw according to package instructions before rolling it out. This prevents cracks and ensures even baking.
What if I don’t have Gruyère or Swiss cheese?
No worries! You can substitute with sharp cheddar, fontina, or even mozzarella in a pinch. Each cheese will lend a slightly different taste, but the tart will still be delicious.
Can I make the caramelized onions ahead of time?
Definitely! You can caramelize the onions a day in advance and store them in the refrigerator. This makes assembling the Caramelized Onion Tart even faster when you’re ready to bake.
Is the goat cheese necessary?
Not at all—it’s optional! The tart is wonderful with just Gruyère or Swiss. Goat cheese or feta simply add a tangy, creamy note that many people love, but you can leave it out if you prefer.
Final Thoughts
I hope you’re as excited as I am to share this Caramelized Onion Tart with your friends and family. It’s a dish that always brings people together with its rich flavors and inviting aroma. Give it a try, and don’t be surprised if it becomes your new favorite go-to for gatherings, brunches, or a cozy night in!
Print
Caramelized Onion Tart Recipe
- Prep Time: 15 minutes
- Cook Time: 55 minutes
- Total Time: 1 hour 10 minutes
- Yield: 6 servings
- Category: Appetizer
- Method: Baking
- Cuisine: French-Inspired
- Diet: Vegetarian
Description
This Caramelized Onion Tart is a deliciously savory French-inspired appetizer featuring sweet, slow-cooked onions on a flaky puff pastry base, topped with melted Gruyère and optional tangy goat cheese. Perfect for brunch or as an elegant starter, this tart offers a wonderful balance of rich flavors and textures.
Ingredients
For the Tart Base
- 1 sheet puff pastry, thawed
For the Caramelized Onions
- 2 tablespoons unsalted butter
- 1 tablespoon olive oil
- 3 large yellow onions, thinly sliced
- 1/2 teaspoon salt
- 1/2 teaspoon sugar
- 1 teaspoon fresh thyme leaves (or 1/4 teaspoon dried thyme)
- Freshly ground black pepper to taste
For the Topping
- 1/2 cup grated Gruyère or Swiss cheese
- 1/4 cup crumbled goat cheese or feta (optional)
- 1 egg, beaten (for egg wash)
Instructions
- Preheat Oven: Preheat your oven to 400°F (200°C) to prepare for baking the tart.
- Caramelize Onions: In a large skillet, melt the butter with the olive oil over medium heat. Add the thinly sliced onions, salt, and sugar. Cook slowly, stirring occasionally, for 25 to 30 minutes until the onions turn deeply golden and caramelized, releasing their natural sweetness.
- Add Thyme and Season: Stir in the fresh thyme leaves and season the onions with freshly ground black pepper to enhance the flavor.
- Prepare Puff Pastry: Roll out the thawed puff pastry on a lightly floured surface. Transfer it to a parchment-lined baking sheet. Lightly score a 1/2-inch border around the edges of the pastry and prick the center with a fork to prevent it from puffing excessively during baking.
- Egg Wash: Brush the scored border of the pastry with the beaten egg to help it brown nicely and create a defined edge.
- Assemble Tart: Spread the caramelized onions evenly within the scored border on the puff pastry. Sprinkle the grated Gruyère cheese evenly over the onions, and if using, crumble the goat cheese over the top.
- Bake: Place the tart in the preheated oven and bake for 20 to 25 minutes, or until the edges of the pastry are golden brown and crisp, and the cheese has melted beautifully.
- Cool and Serve: Allow the tart to cool slightly before slicing. Serve warm or at room temperature, ideal as an appetizer, brunch item, or alongside a green salad.
Notes
- Serve as an appetizer, brunch dish, or alongside a fresh green salad for a complete meal.
- You can prepare the caramelized onions a day ahead and store them in the refrigerator to save time on the day of serving.
- Use goat cheese or feta for a tangier flavor, or omit for a milder taste.
- If you prefer a vegetarian option without cheese, omit the cheeses entirely, though the tart will be less rich.
Nutrition
- Serving Size: 1 slice
- Calories: 280
- Sugar: 5g
- Sodium: 310mg
- Fat: 18g
- Saturated Fat: 9g
- Unsaturated Fat: 8g
- Trans Fat: 0g
- Carbohydrates: 22g
- Fiber: 2g
- Protein: 6g
- Cholesterol: 40mg
