Cook sugar in small saucepan over medium heat until it dissolves and turns golden brown. Remove from heat and stir in butter and vanilla bean seeds.
Pour into ovenproof pan.
Preheat oven to 180°C/360°F. Peel, core, and cut apple into medium-thick slices. Arrange in concentric circles over caramel.
Cut out a circle of puff pastry large enough to cover apples. Score circle all over with the tip of a sharp knife. Place pastry over apples, pressing it down gently to cover.
Transfer pan to oven and bake for approx. 20 - 23 min., or until puff pastry turns golden brown and caramel is bubbling. Turn taste out onto a serving plate and enjoy with a scoop of ice cream of simply on its own!