Prepare an 8-inch square baking pan by lining it with aluminum foil, leaving some overhang to lift the fudge out later.

In a medium, heavy-duty saucepan combine the sugar, evaporated milk, butter (or margarine), and salt. Cook over medium heat, stirring constantly, until the mixture comes to a steady rolling boil.

Once boiling, keep stirring and let the mixture boil steadily for 4 to 5 minutes, then remove the pan from the heat.

Immediately add the miniature marshmallows, chocolate morsels, chopped pecans, and vanilla. Stir vigorously until the marshmallows have melted and the mixture is smooth, about 1 minute.

Transfer the hot fudge into the prepared pan, spreading it evenly. Chill in the refrigerator until completely firm, about 2 hours.

Lift the set fudge from the pan using the foil overhang, remove the foil, and cut into pieces.