Heat olive oil in a pan over medium heat, add sliced onions, and cook until caramelized, about 20 minutes.

Roll out the puff pastry and cut into squares. Place on a baking sheet.

Spread the caramelized onions over the pastry, then sprinkle with goat cheese and thyme.

Bake in a preheated oven at 400°F (200°C) for 15 minutes or until golden brown.