Whisk egg yolks and sugar until mixture is thick and
creamy.
Heat
milk in a saucepan, and when it is almost boiling,
whisk in cocoa powder. Add boiling chocolate milk
gradually to eggs and sugar, stirring continuously,
and mix well. Pass mixture through a sieve.
Pour
into a clean saucepan, and stir over low heat with a
wooden spoon until mixture coats back of spoon.
Transfer mixture to an ice cream churn and churn
until frozen, or pour into freezer tray and freeze,
stirring from time to time.
Press frozen ice cream into a mold and return to
freezer. To serve, dip mold in hot water for a few
seconds and invert ice cream onto chilled plate.
