(Units: 100 g = 3 1/2 oz; 1 dl = 3 1/2 fl oz = 2/5 cup; 180 °C = 350 °F; 200 °C = 400 °F; 230 °C = 450 °F; 250 °C = 475 °F; 2.5 cm = 1 inch)

Make the shortcrust pastry. Line a flan tin with half the pastry and prick the base with a fork.

Boil the elderberry syrup and cornflour, then slightly reduce for 15 minutes and leave to cool.

Sprinkle the ground hazelnuts on top of the pastry base and then pour in the cooled thickened syrup.

Cover with the rest of the pastry and use the egg yolk to seal the edges thoroughly and to brush over.

Bake for 50 minutes at 180 °C.

Serve warm with the sweetened whipped cream.