Getting deep pistachio flavor requires using pistachio butter, or pistachio paste, whose ingredients are strictly pistachios and maybe a little oil. This takes some searching, but this one is good. Eat the gelato within a couple of days. Thanks to Saveur for a great recipe and explanation of pistachio gelato.
In a medium bowl, whisk the egg yolks and sugar until the mixture is thick and pale.
In a medium saucepan, combine the milk, cream, salt, and vanilla over medium heat, cooking just to steaming.
Temper the eggs by whisking in a ladle of the hot milk. Slowly add more hot milk until all of the milk is combined with the egg mixture.
Pour the custard back into the saucepan and cook over medium heat, stirring constantly with a wooden spoon until it is hot (170 degrees F) and slightly thickened. Do the spoon test by running a finger across the spoon that has been dipped in the custard. The line should remain.
Strain the custard into a clean bowl. Stir in the pistachio butter. Chill the custard until it is completely chilled. Do this in the refrigerator overnight, or quickly by placing the bowl of custard (or pour the custard into a ziplock bag) in an ice bath.
Churn the custard in an frozen ice cream maker according to the manufacturer's instructions, until it is very thick and smooth, about 30 minutes. Serve immediately, or scrape into an airtight container and freeze for up to 3 days.
To serve, top scoops of the gelato with crushed raw pistachios. Rose syrup is also delicious over the gelato.