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Puff Pastry Onion Tart

This Puff Pastry Onion Tart is an elegant appetizer made with flaky, golden pastry, tender sweet onions, creamy Greek yogurt, Parmesan, and fresh thyme. The crisp pastry contrasts beautifully with the soft, savory onion topping, creating a simple tart that feels impressive without being complicated.
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Prep Time 15 minutes
Cook Time 35 minutes
Total Time 50 minutes
Servings: 8
Course: Appetizer
Cuisine: French-Inspired
Calories: 245
Ingredients Equipment Method

Ingredients
  

  • 1 sheet frozen puff pastry thawed
  • 2 large sweet onions thinly sliced
  • 1 tablespoon olive oil
  • 2 tablespoons unsalted butter
  • ¼ teaspoon freshly ground black pepper
  • 1 teaspoon balsamic vinegar
  • ⅓ cup plain Greek yogurt
  • ⅓ cup freshly grated Parmesan cheese
  • 1 teaspoon fresh thyme leaves
  • 1 large egg

Equipment

  • Large skillet
  • Baking sheet
  • Parchment paper
  • Sharp knife
  • Rolling pin
  • Pastry brush
  • Mixing bowl
  • Spatula

Method
 

  1. Preheat the oven to 400°F (200°C) and line a baking sheet with parchment paper.
  2. Heat the olive oil and butter in a large skillet over medium heat. Add the sliced onions and salt, then cook for 8 to 10 minutes, stirring occasionally, until softened and lightly golden.
  3. Reduce the heat to medium-low and continue cooking the onions for another 15 to 20 minutes, stirring every few minutes, until deeply softened and caramelized. Stir in the balsamic vinegar and cook for another 2 minutes. Set aside to cool slightly.
  4. Place the thawed puff pastry on a lightly floured surface and gently roll it into a rectangle if needed. Transfer it to the prepared baking sheet.
  5. Using a sharp knife, lightly score a border about 1 inch from the edges without cutting completely through the pastry. Prick the center lightly with a fork to help prevent it from puffing excessively.
  6. Whisk the egg with the water to make an egg wash. Brush the outer border of the pastry lightly with the egg wash, taking care not to let it run down the sides.
  7. Spread the Greek yogurt evenly inside the scored border. Arrange the caramelized onions over the yogurt, then sprinkle evenly with Parmesan cheese and fresh thyme. Season with a little additional black pepper.
  8. Brush the pastry border with another light layer of egg wash. Bake for 20 to 25 minutes, or until the puff pastry is deeply golden, crisp, and fully puffed around the edges.
  9. Allow the tart to cool for about 10 minutes before slicing. Serve warm or at room temperature.