Apple and hazelnut Paris-Brest

1 Heat the oven to 200°C. For the choux pastry, sift the flour with a pinch of salt and set aside.

2 Gently heat the butter, milk and 100 ml water in a heavy-based saucepan until melted. Increase the heat and, just as it reaches boiling point, remove from the heat and mix in all the flour at once. Beat with a wooden spoon until a smooth paste is formed. Return the pan to the heat and continue to beat for 2 mins or until it forms a ball and comes away from the sides. Set aside to cool for 10 mins.

3 Gradually beat in the eggs, mixing well after each addition. Place the mixture in a piping bag and pipe 10 rings of choux (draw circles on the reverse side of the parchment to use as a guide). Sprinkle with the chopped hazelnuts and bake for 20–25 mins.

4 For the filling, whisk the egg yolks until pale, then add the cornflour. Heat the apple juice in a saucepan, then slowly whisk it into the yolks. Transfer the mixture back to the pan, return to the heat and bring to the boil, whisking constantly, until the mixture has thickened. Transfer to a bowl and leave to cool, then chill in fridge until needed.

5 In a food processor, blitz the roasted hazelnuts into a paste. Remove the apple custard from the fridge and whisk in half the hazelnut paste. Transfer the filling to a piping bag fitted with a star nozzle. Put the remaining hazelnut paste in a smaller piping bag.

6 To assemble, cut the choux rings horizontally through the middle and pipe the filling onto the base. Pipe a ring of hazelnut paste over the filling and add the pastry lid. Dust with icing sugar and sprinkle with hazelnuts, to serve.