place the chocolate in a large bowl and set aside. Beat the egg yolks and sugar with a mixer on high speed until pale and creamy. Put the cream and milk in a pan over medium heat and bring to a boil. Remove from heat. Add half the cream mixture to the egg mixture, beating constantly. Return this mixture to the pan with remaining milk and cream and return to the heat. Stir constantly with a wooden spoon until the mixture begins to thicken and coats the back of the spoon. Remove from heat and pour over the chocolate. Stir occasionally until the chocolate is melted and the mixture is thick and smooth. Cover and let cool completely. Place in ice cream machine and churn according to the manufacturer's instructions.
Alternatively, if you don't have an ice cream machine, place mixture in a metal bowl and freeze. When the mixture has just begun set, beat with electric mixer or by hand until creamy. Repeat at least three or four more times. To serve:
Place three glasses per person on six plates. Pour a shot of Bailey's into one glass, a shot of espresso coffee into another and a scoop of chocolate ice cream in the third class. Serve at once. Your guests will choose how they want to combine the three. Traditionally the Bailey's and coffee are poured over the ice cream. Serves six