01 -
Preheat oven to 400°F (200°C).
02 -
Heat olive oil and butter in a pan over medium heat.
03 -
Add onions, sugar, salt, and pepper. Cook until deeply golden and sweet, about 20 minutes, stirring occasionally.
04 -
Stir in balsamic vinegar and thyme. Remove from heat and let cool slightly.
05 -
Roll out puff pastry on a lightly floured surface and cut into 6 equal squares.
06 -
Arrange pastry squares on a parchment-lined baking sheet. Top each square with a generous spoonful of caramelized onions and crumbled goat cheese.
07 -
Bake for 15-20 minutes until pastry is puffed and golden brown.
08 -
Allow to cool slightly before serving warm.