In the bowl of a stand mixer, whip your cream on high until soft peeks are formed (looks like whipped cream)
In a food processor blend on high your pistachios until smooth and creamy. (you may need to add a splash of milk or cream in there depending on how powerful your food processor is)
In a large bowl mix together your condensed milk, pistachio butter, and salt. Then once combined, fold in your whipped cream.
Transfer mixture to a loaf pan and place in freezer for 8 hours or over night.