Steps
1. Preheat oven to 200°C (400°F).
2. Heat olive oil in a skillet over medium heat.
3. Add sliced onions and cook slowly for 15 minutes until caramelized, stirring occasionally.
4. Add balsamic vinegar, salt, pepper, and thyme, cook for another 2 minutes.
5. Roll out puff pastry on a baking sheet lined with parchment paper.
6. Spread the caramelized onions evenly over the pastry, leaving a small border.
7. Crumble goat cheese over the onions.
8. Fold the edges of the pastry slightly inward.
9. Bake for 20-25 minutes until pastry is golden and crisp.
10. Remove from oven and let cool slightly before serving.