Place the flour, butter and icing sugar in a food processor and whizz on the pulse setting until the mixture forms crumbs.
Add the egg yolk and 2-3 tbsp cold water and pulse again until the pastry comes together in a ball. Chill for 10 minutes.
Preheat the oven to Gas 6, 200°C, fan 180°C. Roll out the pastry and use to line a 20cm/8in fluted flan tin.
Line with nonstick baking paper and half fill with baking beans. Bake for 25 minutes, removing the paper and beans for the final 5 minutes and reducing the oven temperature to Gas 4, 180°C, fan 160°C.
In a large bowl, mix the lemon zest and juice together with the sugar, then beat in the cream and eggs.
Pour into the pastry case then return it to the oven and bake for 20-25 minutes or until the filling has set, but is still a bit wobbly. Remove from the oven and leave to cool.
Chill for at least 1 hour before serving and dust with icing sugar.