Combine the cream and milk in a heavy based medium saucepan. Using a small sharp knife, split the vanilla beans in half lengthwise and scrape the seeds from the vanilla beans into the milk mixture, then add the beans to the milk mixture. Bring to a gentle simmer over a medium heat.
Place the egg yolks and sugar in a large bowl and whisk for 2 to 3 minutes or until the mixture is thick and creamy. Gradually whisk the milk mixture into the egg mixture to blend.
Return the custard to the same saucepan and stir in the chocolate. Cook the custard over a medium to low heat, stirring constantly, for about 10 minutes, or until the custard coats the back of the spoon. Do not allow the custard to boil or it will curdle. Strain the mixture through a fine-meshed sieve and into a large bowl.
Set the bowl of ice cream base over another large bowl of ice water and stir the mixture until it is cold, then stir in the coconut.
Pour the mixture into an ice cream machine and process according to the manufacturer’s instructions or until it is almost set, remove ice cream from machine to a storage container and freeze ice cream covered until serving.