Ice cream mixture
In a pan, whisk together the eggs and sugar, bring to just below the boil over a medium heat, stirring constantly. As soon as the mixture thickens, remove the pan from the heat.
Pour ⅓ of the mixture into a bowl, mix together with the Baileys and espresso.
Beat the cream with the sugar until stiff. Fold half of the whipped cream carefully into the espresso mixture, cover and chill. Fold the remainder of the whipped cream into the egg mixture, pour ½ into the prepared tin, cover and freeze for approx. 2 hrs. Cover and chill the remaining mixture.
Place the chocolate in a thin-sided bowl and suspend over a gently simmering bain-marie, ensuring that the bowl does not touch the water. Melt the chocolate and stir until smooth. Pour ⅓ of the chocolate over the frozen mixture, spread the coffee mixture on top, cover and freeze for approx. 2 hrs. Spread ⅓ of the chocolate on top, pour the remaining egg mixture over the top, freeze for approx. 2 hrs. Pour the remainder of the chocolate over the top, cover and freeze for approx. 12 hrs. Sprinkle with cocoa powder.