Set the pistachios on a sheet pan and preheat the oven to 350 F.
Toast the nuts for 10 minutes, shaking the pan halfway, until very hot and fragrant.
Set the nuts in a food processor and blend on high until you have a loose paste, this can take up to 30 minutes, depending on the strength and power of your food processor. Scrape down as needed to ensure all the nuts are being processed.
Add the sweetened condensed milk to the food processor and milk and process until smooth.
Separately, pour the cold heavy cream into a large bowl, add the vanilla and salt, and use a hand mixer to whip to medium to stiff peaks, you’ll see ribbons forming in the cream and when you lift the mixer the cream will slowly droop.
Add the pistachio milk mixture, slowly while the mixer is on, and whip until fully combined.
Transfer to a freezer safe airtight container.