In a large bowl, stir together the sweetened condensed milk, vanilla, and salt until blended.
In another bowl, beat the heavy cream until stiff peaks form.
Fold the whipped cream into the sweetened condensed milk mixture, using a spatula to gently bring up the mixture from the sides and bottom, then folding over toward the middle. Fold until mixed and no streaks remain. Do not stir hard, which will cause the volume to collapse.
Pour the ice cream mixture into containers, place on lids, and freeze for 4-6 hours before serving.