Combine half of the milk with the cream and vanilla pod and bring to the boil. In a bowl, whisk together the remainder of the milk, egg yolks and sugar. Whisk approx. 100 ml of the hot milk into the egg yolk mixture. Return everything to the pan and bring to just below the boil, stirring constantly. Remove the pan from the heat, stir for approx. 2 mins., then pour the custard into a stainless steel bowl through a sieve.
Blanch the basil in boiling water for approx. 30 secs., remove, dip briefly in ice-cold water, drain well. Puree the basil with the milk, stir into the custard. Cover and freeze for approx. 4 hrs., stirring three times. Stir in the chocolate and freeze for approx. 1 hr.
Shape the ice cream into balls, serve in bowls, garnish with basil.