Whisk together the condensed milk, vanilla and salt in a large bowl; set aside. Whip the cream with a mixer on medium-high speed until firm peaks form, about 2 minutes. Fold about 1 cup of the whipped cream into the condensed milk mixture with a rubber spatula until combined, then fold the lightened mixture into the whipped cream until well blended. Pour into a chilled 9-by-5-by-3-inch meat loaf pan. Freeze, covered, until solid and scoopable, about 5 hours.