These upside-down caramelized onion and brie tarts are the definition of simple comfort food. Sweet, deeply caramelized onions melt into creamy brie, all wrapped in flaky, buttery puff pastry. They look impressive, taste indulgent, and come together with minimal effort—perfect for weekends, gatherings, or a cozy treat at home.
Why You’ll Love This Recipe
This recipe delivers big flavor with very little work. The onions become rich and sweet as they caramelize, balancing perfectly with the mild creaminess of brie. Puff pastry does all the hard work for you, baking up golden and crisp. These tartlets are versatile enough to serve as an appetizer, light meal, or elegant snack, and they’re ready in under 30 minutes from start to finish.
Ingredients
(Tip: You’ll find the full list of ingredients and measurements in the recipe card below.)
For the tartlets
1 sheet puff pastry, thawed
2 large onions, thinly sliced
1 tablespoon olive oil
1 tablespoon butter
1 tablespoon brown sugar
1 tablespoon balsamic vinegar
100 g (3.5 oz) brie cheese, sliced
To finish
1 to 2 teaspoons fresh thyme leaves
Sea salt, to taste
Cracked black pepper, to taste
Directions
Preheat the oven to 390°F (200°C). Line a baking tray with parchment paper and set aside.
Heat the olive oil and butter in a skillet over medium heat. Add the sliced onions and cook slowly, stirring occasionally, for about 10 minutes until softened and translucent.
Stir in the brown sugar and balsamic vinegar. Continue cooking for another 5 to 7 minutes, until the onions are deeply caramelized and glossy. Remove from heat and let cool slightly.
Cut the puff pastry sheet into 6 equal squares.
On the prepared baking tray, spoon 6 small mounds of caramelized onions, spacing them apart. Place a slice of brie on top of each mound.
Cover each onion-and-brie mound with a square of puff pastry, gently tucking the edges underneath to encase the filling.
Prick the top of each pastry square with a fork to allow steam to escape.
Bake for 15 to 18 minutes, or until the pastry is puffed and golden brown.
Remove from the oven and let rest for 2 minutes. Carefully flip each tartlet over so the onion and brie are on top.
Finish with fresh thyme, a pinch of sea salt, and cracked black pepper before serving.
Servings and timing
Servings: 6 tartlets
Prep time: 10 minutes
Cook time: 18 minutes
Total time: approximately 28 minutes
Variations
You can add a touch of sweetness by sprinkling a few dried cranberries or chopped dates into the onions before assembling. For extra depth, mix a teaspoon of Dijon-style mustard into the caramelized onions. If you prefer a stronger herb note, rosemary or oregano can be used instead of thyme.
Storage/Reheating
Store leftover tartlets in an airtight container in the refrigerator for up to 3 days. To reheat, place them in a preheated oven at 350°F (180°C) for 8 to 10 minutes until warmed through and crisp again. Avoid microwaving, as it can make the pastry soggy.
FAQs
Can I make these tarts ahead of time?
Yes, you can caramelize the onions up to 2 days in advance and store them in the refrigerator. Assemble and bake the tartlets just before serving for best results.
Can I use a different cheese instead of brie?
Yes, camembert or a mild soft cheese works well, as long as it melts smoothly.
Do I need to grease the parchment paper?
No, parchment paper prevents sticking and makes flipping the tartlets much easier.
Why are these tarts baked upside-down?
Baking them upside-down allows the onions to caramelize further in the oven and creates a beautiful presentation when flipped.
Can I make this recipe vegetarian?
The recipe is already vegetarian as written.
How thin should the onions be sliced?
Thin slices are best, about 1/8 inch thick, so they cook evenly and caramelize properly.
Can I freeze the baked tartlets?
Freezing is not recommended, as the puff pastry can lose its crisp texture when thawed.
What can I serve with these tartlets?
They pair well with a fresh green salad or a light soup for a complete meal.
Can I reduce the sweetness?
Yes, you can slightly reduce the brown sugar or omit it, though the onions may be less deeply caramelized.
How do I prevent the pastry from opening during baking?
Tucking the pastry edges firmly under the filling and pricking the tops with a fork helps keep them sealed.
Conclusion
Upside-down caramelized onion and brie tarts are proof that simple ingredients can create something truly special. With their flaky pastry, rich onions, and creamy cheese, they’re an easy yet elegant dish you’ll want to make again and again, whether for guests or a quiet night in.
These upside-down caramelized onion and brie tarts are a simple yet elegant dish featuring sweet, rich onions and creamy brie encased in golden puff pastry. Perfect as an appetizer, snack, or light meal, they’re easy to make and full of comforting flavor.
Ingredients
1 sheet puff pastry, thawed
2 large onions, thinly sliced
1 tablespoon olive oil
1 tablespoon butter
1 tablespoon brown sugar
1 tablespoon balsamic vinegar
100 g (3.5 oz) brie cheese, sliced
1–2 teaspoons fresh thyme leaves
Sea salt, to taste
Cracked black pepper, to taste
Instructions
Preheat the oven to 390°F (200°C) and line a baking tray with parchment paper.
Heat olive oil and butter in a skillet over medium heat. Add sliced onions and cook for about 10 minutes, stirring occasionally, until softened.
Stir in brown sugar and balsamic vinegar. Cook for another 5–7 minutes until the onions are deeply caramelized. Remove from heat and let cool slightly.
Cut puff pastry into 6 equal squares.
Spoon 6 small mounds of caramelized onions onto the parchment-lined tray, spaced apart. Top each with a slice of brie.
Place a puff pastry square over each mound, tucking edges underneath to encase the filling.
Prick the tops with a fork to allow steam to escape.
Bake for 15–18 minutes or until puffed and golden brown.
Let rest for 2 minutes, then carefully flip each tart so the onion and brie are on top.
Garnish with thyme, sea salt, and black pepper. Serve warm.
Notes
Caramelize onions in advance for quicker prep.
Try camembert or soft goat cheese as a substitute for brie.
Add chopped dates or dried cranberries for a sweet twist.
A touch of Dijon mustard in the onions adds depth.
