Instructions

1. Line the bottom of a 20 cm (8 inch) springform cake tin with baking paper and grease the sides with butter.
2. Roll out the first sheet of puff pastry to fit the base of the cake tin.
3. Roll out the second sheet of puff pastry into a long rectangle 15 cm (6 inches) high and long enough to line the side of the cake tin. You may need to do this in two strips. Line the sides of the cake tin with the pastry strips, allowing for some overlap where they join up and also where they meet with the base.
4. Press down on the overlaps with your fingertips to seal the edges.
5. Use a sharp knife to cut out triangles from the sides of the cake tin to resemble a crown, leaving a band of at least 3.5 cm (1.5 inches).
6. Place the cake tin in the fridge for 30 minutes.
7. Toast the hazelnuts until golden. Leave to cool slightly before processing finely in a food processor.
8. Add the caster sugar, salt, egg, and butter, and process until smooth.
9. Spread the mixture over the base of the lined cake tin.
10. Hide the fève in the frangipane.
11. Peel, core and thinly slice the apple and arrange the slices on top of the frangipane.
12. Place the cake tin back in the fridge and chill for another 30 minutes.
13. Place a baking tray in the oven and preheat the oven to 200°C (390°F).
14. Place the cake tin on the hot baking tray, and reduce the temperature to 180°C (355°F).
15. Bake for about 45 minutes or until the pastry is golden brown.
16. Heat a few tablespoons of apricot jam or honey in a small saucepan and brush over the cooked apple to make it glossy.