Place a 9” x 5” x 3” metal loaf pan or a similar freezer-safe container in the freezer to chill.
In a large bowl, whisk together the sweetened condensed milk, brown sugar, vanilla extract, and salt.
In a separate bowl, use an electric mixer to whip the heavy cream until firm peaks form.
Gently fold about a cup of the whipped cream into the condensed milk mixture. Then, transfer this combined mixture back into the remaining whipped cream and fold gently to mix.
Spread the mixture evenly in the chilled pan, cover tightly, and place it in the freezer for 2 hours.
Preheat the oven to 350°F (175°C) and line a baking sheet with parchment paper or a silicone liner.
Toss the chopped pecans with melted butter until well coated. Spread them in a single layer on the prepared baking sheet and bake for 12 to 15 minutes, or until toasted. Let them cool completely.
After the ice cream has chilled for 2 hours, remove it from the freezer and stir in the cooled pecan pieces. Save some for sprinkling on top, if desired. Cover and return the pan to the freezer for at least 3 more hours before serving.