Golden Flaky Caramelized Onion & Gruyère Pinwheels with Thyme-Balsamic Glaze

These Golden Flaky Caramelized Onion & Gruyère Pinwheels are a show-stopping appetizer that's surprisingly simple to make. Layers of rich, sweet caramelized onions, nutty Gruyère cheese, and fresh thyme are baked into golden puff pastry. A drizzle of tangy balsamic glaze adds the perfect finishing touch to these savory, crowd-pleasing bites.

Prep Time 20 minutes

Cook Time 35 minutes

Total Time 55 minutes

Servings 4 servings

Ingredients

• 1 tbsp olive oil
• 2 large yellow onions, thinly sliced
• 1/2 tsp salt
• 1/4 tsp black pepper
• 1 sheet frozen puff pastry (from a 14.1 oz package), thawed
• 1/2 cup (about 2 oz) shredded Gruyère cheese
• 1 tbsp fresh thyme leaves, finely chopped
• 1 large egg, beaten (for egg wash)
• 2 tbsp balsamic glaze (store-bought or homemade)

Instructions

1. Heat olive oil in a large skillet over medium-low heat. Add sliced onions, salt, and pepper. Cook, stirring occasionally, for 25-30 minutes, or until deeply golden brown and caramelized.
2. Preheat oven to 400°F (200°C). Line a baking sheet with parchment paper.
3. On a lightly floured surface, unroll the thawed puff pastry. If needed, gently roll it into a 10x12-inch rectangle.
4. Spread the cooled caramelized onions evenly over the puff pastry, leaving a 1/2-inch border along one long edge.
5. Sprinkle the Gruyère cheese and chopped fresh thyme over the onions.
6. Starting from the long edge opposite the border, tightly roll the puff pastry into a log. Moisten the un-bordered edge with a little water or egg wash to seal.
7. Using a sharp knife, slice the log into 12 equal pinwheels, about 1-inch thick. Arrange the pinwheels cut-side up on the prepared baking sheet.
8. Brush the tops and sides of each pinwheel with the beaten egg wash.
9. Bake for 18-22 minutes, or until the pastry is golden brown and puffed.
10. Remove from oven, let cool slightly, then drizzle with balsamic glaze before serving warm.

Chef's Note

For perfectly caramelized onions, resist the urge to rush the process. Low and slow heat is key to developing their deep, sweet flavor. If your onions start to stick, add a tablespoon of water or broth to deglaze the pan.

Make-Ahead Tips

You can caramelize the onions up to 3 days in advance and store them in an airtight container in the refrigerator. Assemble the pinwheels just before baking for the best flaky texture.

Substitutions

Feel free to swap Gruyère for other hard cheeses like Parmesan or sharp white cheddar. Rosemary or sage can be used instead of thyme. For a touch of sweetness, a thin layer of fig jam can be spread over the pastry before the onions.