Place a 9” x 5” x 3” metal loaf pan or similarly sized freezer-safe container in the freezer.
Whisk together the condensed milk, brown sugar, vanilla, and salt in a large bowl.
In a separate bowl, whip the cream with an electric mixer on medium-high speed until firm peaks form.
Fold about a cup of the whipped cream into the condensed milk mixture. Transfer that mixture to the remaining whipped cream and fold gently to combine.
Spread the mixture in the chilled pan. Cover tightly and place in the freezer for 2 hours.
Heat the oven to 350°F. Line a baking sheet with parchment paper or a silicone liner.
Combine the pecans and melted butter until thoroughly coated. Spread in a single layer and bake for 12 to 15 minutes or until toasted. Set aside to cool completely.
After the ice cream has chilled for 2 hours, remove from the freezer and stir in the pecan pieces. Save some pieces for sprinkling over the top, if you like. Cover and return to the freezer for at least 3 hours before serving.