In a food processor, combine the pistachios and sugar and process until finely ground, about 45 seconds. Set aside.
In a medium heat-proof bowl, whisk the egg yolks until smooth. Set aside.
In a large saucepan, heat the cream, milk, salt, and ground pistachio mixture over medium heat, stirring occasionally, until the mixture is warm and the sugar has dissolved, about 5 minutes.
Gradually whisk in about a cup of the warm cream mixture into the egg yolks. Whisk the egg yolk mixture into a saucepan with the rest of the warm cream.
Cook over medium heat, gently stirring constantly, until the mixture is thickened, coats the back of a spoon, and a thermometer inserted registers 170°F, about 5 minutes.
Pour through a fine mesh sieve set over a medium bowl, pressing with a rubber spatula to strain out as much liquid as possible from the pistachios. Discard the remaining solids in the sieve.
Stir the vanilla and almond extract into the cream base. Coll, stirring occasionally, until mixture cools to room temperature. Cover and refrigerate until fully chilled, at least 1 hour or up to 24 hours.
Pour the chilled pistachio ice cream base into an ice cream maker and churn according to the manufacturer’s instructions. Spoon the churned ice cream into a freezer-safe 1-quart container. Stir in additional chopped pistachios, if desired. Cover and freeze until firm, 4 to 6 hours.
Notes
For a brighter green color: Add a drop or two of green food coloring along with the extracts to the ice cream base. I like the natural pale yellowish-brown color of the ice cream without food coloring because it looks just like ground pistachios. But a little bit of enhanced green color makes a really pretty presentation.
Add more pistachios: If desired, stir in chopped pistachios after churning. You could also sprinkle some on top of each serving as well.
Strain the custard. Straining the ice cream base will catch any pieces of egg or solid custard, so all that remains is a velvety smooth liquid with no chunks.
Chill the ice cream base before churning. The liquid base must be cold so it churns well. Pouring hot custard into a frozen ice cream maker will melt the frozen insert before the base freezes into ice cream.
Freeze the ice cream before serving. Once the ice cream is churned, it needs to be frozen for a few hours until solid. It will still be very soft right after churning. A few hours in the freezer will make it perfectly scoopable.