Put the milk and cream in a saucepan over medium heat and bring to the boil. Remove from the heat.
Combine the egg yolks and sugar in a heatproof bowl. Pour the hot milk mixture into the bowl and stir to combine well. Pour this back into the pan and return to a low heat. Stir the custard constantly with a heat-resistant spatula and cook to 82°C (180°F); use a d