Wash and cut the apple into thin slices and arrange in the center of the rectangle of dough, overlapping with each other.
Sprinkle the brown sugar and cinnamon over them .
Add a spoonful of jam slightly diluted with hot water to make it more liquid.
Bake the pastry into the preheated oven at 180°C for 10 minutes.
Remove from the oven, allow to cool and sprinkle with icing sugar.