225g/8oz plain flour, plus extra for dusting
100²µ/3Β½΄Η³ϊ caster sugar
40²µ/1Β½΄Η³ϊ cornflour
200g/7oz icing sugar
Β½ tsp salt
1 vanilla pod, split down the middle and seeds scraped out
50g/2oz dark chocolate, melted
200g/7oz butter, chilled and cut into 1cm/Β½in cubes
40²µ/1Β½΄Η³ϊ butter
4 free-range eggs, yolks only
500ml/18fl oz milk