Ingredients:

  • 2 large Yellow Onions (about 1 lb / 450 g), finely sliced
  • 2 Tbsp Unsalted Butter
  • 1 Tbsp Olive Oil
  • 1 tsp Brown Sugar (optional)
  • 1 tsp Fresh Thyme Leaves, removed from the stem
  • Salt & Black Pepper, To taste
  • 1 sheet Ready-Rolled Puff Pastry (14.1 oz / 400 g), cold
  • 4 oz Aged Gouda Cheese (115 g), finely grated
  • 1 Large Egg, for the egg wash
  • 1 tsp Water or Milk, to dilute the egg wash

Instructions:

  1. Sauté Slowly: Heat the butter and olive oil in the sauté pan over medium-low heat. Add the sliced onions and a generous pinch of salt. Cook, stirring occasionally, for 20–25 minutes until the onions are deep golden brown and heavily reduced in volume. Do not rush this step; low and slow is key.
  2. Season: Stir in the brown sugar (if using) and the fresh thyme leaves. Cook for 2 more minutes. Season aggressively with pepper.
  3. Cool: Transfer the caramelized onions to a bowl or plate and spread thinly. Place in the refrigerator and allow to cool completely—about 30 minutes. A warm filling will melt the pastry.
  4. Prepare Pastry: Preheat the oven to 400°F (200°C). Line two baking sheets with parchment paper. Unroll the chilled puff pastry onto a lightly floured surface.
  5. Spread Filling: Gently spread the completely cooled caramelized onion mixture evenly over the entire surface of the pastry sheet, leaving a 1 cm (½ inch) border along the longest edge.
  6. Add Cheese: Sprinkle the grated Gouda evenly over the onion layer.
  7. Roll Tightly: Starting from the long edge opposite the border, tightly roll the pastry into a log. Brush the un-filled border with a little water, and press gently to seal the seam completely.
  8. Chill (Crucial Step): Wrap the pastry log tightly in cling film and place it in the freezer for 15 minutes, or the refrigerator for 45 minutes. This ensures the log is firm and holds its shape for clean slicing.
  9. Slice: Remove the log from the chiller. Using a very sharp knife (or strong dental floss), slice the log into 24 even discs, approximately 1 cm (½ inch) thick.
  10. Arrange: Lay the pinwheels flat on the prepared baking sheets, leaving a slight gap between each piece.
  11. Glaze: Whisk the egg with 1 teaspoon of water or milk to create the egg wash. Brush the top surface of each pinwheel lightly with the wash for a golden finish.
  12. Bake: Bake for 18–22 minutes, rotating the trays halfway through, until the pastry is puffed up, golden brown, and the cheese is bubbling.
  13. Serve: Cool slightly on the tray before serving warm or at room temperature.