For the pastry
For the filling
To make the pastry, sift the flour into a mixing bowl, make a well in the centre and put the butter, sugar and egg yolks in it. Work with the fingertips of one hand until these are blended, then gradually work in the flour. Continue mixing until the pastry forms a smooth ball. Wrap in cling film and chill for 30 minutes.
Preheat the oven to 190°C/375°F/Gas mark 5. Grease a 28cm/11in flan dish.
Roll out the pastry and use to line the tin. Prick the base of the pastry with a fork, and line with foil. Fill with baking beans and bake blind for 15–20 minutes until just brown. Remove from the oven to cool, and reduce the oven temperature to 160°C/325°F/Gas mark 3.
To make the filling, put the lemon zest in a large bowl with the lemon and orange juice. Add the eggs and yolk, cream and sugar. Whisk the mixture together until the sugar has dissolved and the top is fluffy. Pour the filling into the pastry case and bake in the centre of the oven for 30–35 minutes until the filling is set. Serve warm or cold.