Blend the pistachios in a food processor and add 4 tablespoons of milk until you obtain a creamy mixture.
In a saucepan mix the milk (200 ml) and cream and heat over low heat. Add the pistachios. Measure the temperature with a cooking thermometer. It should not exceed 85 °C (185 °F). Cook for 5-6 minutes. Remove from the heat and let rest for 45 minutes.
Beat the egg yolks and the sugar with a wisk. The yolks should be creamy and pale yellow.
Heat the milk, cream and pistachios mixture again to reach the temperature of 85°C (185°F). Filter using a sieve. Add the milk to the egg yolk mixture, stirring slowly. Cook for a few minutes then remove from the heat and let cool completely, stirring a few times with a spoon.
If you have an ice cream maker pour the mixture into ice cream maker and follow the instructions.
If you do not have an ice cream maker, pour the mixture in a suitable container and store in the freezer for at least three hours. Remove from the freezer, stir and put back in the freezer for another three hours. At this point, the ice cream is ready. To give it a creamier texture blend for a few seconds and then put in the freezer for about 10 minutes.