Whip the egg yolks and sugar together until thick and creamy
Place the milk into a medium sized saucepan and bring to the boil
Add the milk to the eggs and sugar while stirring continuously
Return to the pan and cook over a low heat until thickened

Add the chocolate and stir until melted
Pour in the cream and espresso
Remove from the heat and allow to cool
Chill in the fridge

Churn in an ice-cream maker for 20 minutes
Place in the freezer for a couple of hours until frozen