For the apple tartins, peel the apples and cut them into small pieces. Bring the water with the sugar to a boil and let it reduce to caramel.
Roll out the puff pastry thinly and cut out with a small ring (the ring should be slightly smaller than the muffin cups). Put a tablespoon of caramel in each muffin cup and place a few apple pieces on top. Place one cut out puff pastry circle on each caramel-apple mound and press down lightly.
Bake the muffin tray in the preheated oven at 160°C for about 10 minutes. Let cool slightly and turn out carefully. Sprinkle the apple tartins with powdered sugar and arrange on a platter or plate.
Preparation Tip:
How to peel the apples quickly and easily, you can see in this video.