Preheat your oven to 180°C (350°F).

In an oven-safe skillet or tart pan, melt butter over medium heat. Sprinkle sugar evenly over the melted butter and cook until it turns golden and caramelized.

Arrange apple quarters in a circular pattern over the caramel. Sprinkle with cinnamon if desired. Cook for 5-7 minutes.

Roll out the puff pastry and place it over the apples, tucking in the edges. Prick the pastry with a fork to release steam.

Bake for 30-35 minutes, or until the puff pastry is golden and crisp.

Let the tart cool for 5 minutes, then carefully invert it onto a serving plate to reveal the caramelized apples. Serve warm.