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Onion Tarts Recipe

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These Onion Tarts combine crisp, flaky puff pastry with sweet caramelized onions, nutty Gruyere, and fresh thyme. They make an elegant savory appetizer for holidays, brunches, parties, or a light meal.

Ingredients

  • 1 sheet puff pastry, thawed
  • 2 large yellow or sweet onions, thinly sliced
  • 1 tablespoon unsalted butter
  • 1 tablespoon olive oil
  • 1 cup shredded Gruyere cheese
  • 1 teaspoon fresh thyme leaves, plus more for garnish
  • 1/4 teaspoon salt
  • 1/4 teaspoon freshly ground black pepper
  • 1 large egg
  • 1 tablespoon water
  • 2 tablespoons balsamic glaze, optional
  • 2 tablespoons chopped fresh parsley, optional

Instructions

  1. Heat the butter and olive oil in a large skillet over medium-low heat.
  2. Add the thinly sliced onions and salt. Cook for 25 to 35 minutes, stirring occasionally, until the onions are very soft and deeply golden.
  3. If the onions begin sticking, add a small splash of water and scrape up the browned bits from the bottom of the skillet. Keep the heat low enough to caramelize the onions without burning them.
  4. Stir the fresh thyme and black pepper into the caramelized onions. Remove the skillet from the heat and allow the onions to cool slightly.
  5. Preheat the oven to 400°F (200°C) and line a large baking sheet with parchment paper.
  6. Unfold the thawed puff pastry onto a lightly floured surface and gently roll it to smooth any creases. Cut the pastry into 8 equal squares or rectangles.
  7. Transfer the pastry pieces to the prepared baking sheet. Lightly score a border approximately 1/2 inch from the edge of each piece without cutting completely through the pastry.
  8. Prick the center of each tart several times with a fork, keeping the scored borders intact.
  9. Divide the shredded Gruyere among the tarts, keeping it inside the borders. Spoon the cooled caramelized onions evenly over the cheese.
  10. Whisk the egg with 1 tablespoon water and lightly brush the exposed pastry borders with the egg wash.
  11. Bake for 15 to 20 minutes, until the pastry is puffed and deeply golden and the Gruyere has melted.
  12. Let the tarts cool for a few minutes. Garnish with additional fresh thyme, parsley, or balsamic glaze if desired and serve warm.

Notes

  • Yellow or sweet onions work especially well because they become mild, sweet, and flavorful when slowly caramelized.
  • Keep the heat at medium-low or low while caramelizing the onions. High heat can burn them before they soften properly.
  • Let the caramelized onions cool slightly and avoid transferring excess liquid to the pastry to help prevent soggy tarts.
  • Gruyere can be replaced or combined with goat cheese, Parmesan, feta, Swiss, or fontina.
  • For bacon and onion tarts, add fully cooked and crumbled bacon before baking.
  • Cook mushrooms, spinach, or other moisture-rich vegetables before adding them to the tarts.
  • The caramelized onions can be prepared ahead and refrigerated until ready to assemble the tarts.
  • Store leftover tarts in an airtight container in the refrigerator for up to 3 days.
  • Reheat in a 350°F (175°C) oven for 5 to 8 minutes or in an air fryer for a few minutes to restore the crisp pastry texture.

Nutrition

Find it online: https://thefamilycooking.com/onion-tarts-recipe/