Ingredients:

  • 2 tbsp (28g) unsalted butter
  • 2 large yellow onions, thinly sliced (approx. 300g)
  • 1 tbsp (15ml) balsamic vinegar
  • ½ tsp (3g) kosher salt
  • ¼ tsp (1g) black pepper
  • 1 sheet (approx. 17 oz / 480g) frozen puff pastry
  • 1 large Granny Smith apple, cored and thinly sliced (approx. 150g)
  • 7 oz (200g) Brie cheese
  • 1 tbsp (15ml) egg wash (1 egg beaten with 1 tsp water)

Instructions:

  1. Melt the butter in a skillet over medium-low heat. Add the sliced onions and salt. Cook slowly, stirring occasionally, for about 15–20 minutes until the onions turn a deep, mahogany-colored brown.
  2. Stir in the balsamic vinegar and pepper, cooking for 1 more minute until the liquid has evaporated and the onions are jammy. Remove from heat and let cool slightly.
  3. Preheat your oven to 400°F (200°C).
  4. Roll out the puff pastry onto a parchment-lined baking sheet. Using a knife, lightly score a 1-inch border around the edge of the pastry—do not cut all the way through.
  5. Prick the center area (inside the border) several times with a fork to prevent the middle from puffing up too much.
  6. Spread the caramelized onions evenly within the scored border.
  7. Layer the apple slices in an overlapping pattern over the onions.
  8. Top the apples with the Brie slices.
  9. Brush the outer border of the pastry with egg wash for a glossy, golden finish.
  10. Bake for 20–25 minutes, or until the pastry is golden brown and crisp.