1.5 kg (3 lb) apple, preferably Honeycrisp or Granny Smith
100 g (½ cup) caster sugar
3 tablespoons unsalted butter
ice cream, to serve
Using a 9-inch (23 cm) pan, cut a circle out from the puff pastry. Using a fork, poke holes all over to provide ventilation. Set aside.
Peel and quarter the apples, removing the stems and cores.
Preheat oven to 375°F (190°C).
In a large saucepan over medium heat, distribute the sugar evenly and cook until a light amber color, stirring to help melt any lumps.
Add the butter, stirring constantly until the color is a creamy light brown.
Add the apples, making sure the juices from the apples help dissolve any caramel that sticks to the apples.
Cook for about 15-20 minutes, making sure the apples are turned constantly so that they bathe in the caramel. Remove from heat when the caramel has reduced to completely glaze the apples and little remains in the bottom of the pan. Be sure not to burn the caramel, tasting it from time to time to ensure it does not taste bitter.
Arrange the apples in concentric circles on the bottom of the pan. Press the apples tightly against each other, then pour the glaze over the top.
Lay the circle of puff pastry on top. Tuck the puff pastry down the sides of the pan.
Bake for 45-50 minutes, until the pastry is golden brown and firm.