Prepare Pistachio Paste: Process in a blender or food processor until you have a coarsely ground paste of pistachios (you will need to use some cream or milk while making this for it to blend well). Set aside.
Heat Milk and Cream: 1. Combine the heavy cream and milk in a medium -saucepan. 2. Bring to a simmer over medium (do not boil).3. Stir occasionally. Whisk Egg Yolks and Sugar: Whisk together the egg yolks and sugar until pale and slightly thickened while the cream mixture is heating.
Temper the Egg Yolks: Whisk them constantly, slowly pouring in a little bit of the hot cream mixture as you add it to the yolks. This only works if you are whisking continuously, or else they will curdle! After the yolks are warmed, continue to whisk them while slowly pouring them back into the saucepan with the rest of the hot cream mixture.
Cook the Custard: In a small saucepan, over medium heat and stirring constantly with a wooden spoon, cook the custard mixture until it slightly thickens and coats the back of the spoon (170-175˚F/77-80˚C)
Strain the Custard: Strain the custard through a fine-mesh sieve into another bowl to remove curdled egg bits.
Add Pistachio Paste: Fold in the pistachio paste & vanilla extract. The salt will round out the flavor. Combine thoroughly until the paste is combined.
Chill the Custard: Allow the mixture to cool to room temperature, cover, and refrigerate for at least 4 hours (overnight is ideal).
Churn the Ice Cream: After it has cooled, churn the custard in an ice cream maker according to manufacturer instructions (about 20–30 minutes).
Freeze the Ice Cream: Scoop the churned ice cream into a container and freeze for at least 4 hours or until solid.