If you can’t find pistachio paste, you can make your own by pounding freshly skinned pistachios in a mortar to make a smooth paste.
500ml (2 cups) milk
500ml (2 cups) whipping cream
60g (2oz) pistachio paste
150g (¾ cup) caster (superfine) sugar
200g (7oz) egg yolks (about 10)
70g (6 tbsp) demerara sugar
Preheat the oven to 120°C/250ºF/Gas ½. To make the custard, heat the milk, cream, pistachio paste and 90 g (scant ½ cup) caster sugar in a saucepan, whisking until well blended, then slowly bring to the boil.
Meanwhile, in a bowl, lightly whisk the egg yolks with the remaining caster sugar. As soon as the milk mixture comes to the boil, gradually pour it on to the egg mixture, whisking all the time.
Ladle the custard into 15 cm (6in) gratin dishes and place on a baking tray. Cook in the oven for 30 minutes, or until just set. Transfer the dishes to a wire rack and leave until the custards are cold, then chill until ready to serve.
Just before serving, sprinkle the tops with the demerara sugar and caramelise with a cook’s blowtorch, or under a very hot grill (broiler), to make a thin, pale nut-brown topping. Serve immediately.
