Line a springform pan (25 cm in diameter) with baking paper, butter the rim. Preheat the oven to 200°C. Beat the butter, icing sugar and eggs until light and fluffy. Add the chestnut puree. Add the nuts, vanilla sugar and baking powder, stir briefly. Transfer the mixture to the prepared tin.
Bake the chestnut cake for approx. 45 mins. in the centre of the preheated oven. Remove the cake from the oven, allow to cool slightly, remove the tin frame, slide onto a cooling rack and leave to cool. Cut the chestnut cake into slices and dust with icing sugar.
Apple juice cream
Bring the eggs, sugar, vanilla sugar, cornflour and apple juice to the boil while stirring. Bring to just below the boil, stirring constantly. Remove the pan from the hob and continue to stir for a moment. Strain the cream into a bowl and set aside until cold. Before serving, cover and chill for at least 1 hr. Shortly before serving, add the lemon zest and a few dashes of lemon juice. Beat the double cream until stiff and loosely fold into the apple cream.