In a small bowl mix together the vanilla extract, salt and sweetened condensed milk until combined.
In a mixing bowl, use a hand mixer with whisk attachment to whip the heavy cream to soft-medium stiff peaks.
Pour the sweetened condensed milk mixture and desired crumbled feta cheese into the whipped cream mixture and gently fold everything together. Be careful not to overmix.
Pour half of the mixture into the prepared loaf pan, add 1/4 cup pistachio cream and 1 1/2 tbsp chopped pistachios and use a toothpick to gently swirl it into the mixture. Pour in the remaining ice cream mixture and top with 1/4 cup pistachio cream and 1 1/2 tbsp chopped pistachios. Again use a toothpick to swirl it into the mixture.
Cover tightly with plastic wrap and freezer for at least 8 hours or overnight before serving.
Video
Notes
Pistachio cream can be found in most stores or local Italian Markets.
In a pinch, you can double the amount of pistachios if you can't find pistachio cream.