Place milk, 1 cup of cream, sugar, salt, and ground pistachios in a medium sauce pan. Heat until the mixture is steaming, but not boiling. Remove from heat and cover for 1 hour to let the pistachios steep in the milk.
Once mixture has steeped for 1 hour, place saucepan back over heat so it's steaming again. Remove from heat. Whisk egg yolks in a medium bowl until combined. Very slowly whisk in warm milk. Transfer mixture back to saucepan and set over medium heat. Stir constantly until mixture begins to thicken and is between 168-170 degrees. Mixture should coat the back of the spatula. Remove from heat immediately so the mixture doesn't scramble.
Place remaining heavy cream in a large bowl and place strainer over bowl. Pour thickened yolk mixture through strainer to remove lumps and large chunks of pistachios. Stir with cream and almond extract to cool the mixture down.
Chill mixture in the refrigerator until completely cold, about 4-6 hours. Once chilled, ice cream base is ready for your machine. Freeze ice cream according to machine instructions. Transfer to storage container and freeze until firm, about 6-8 hours.