Line an 8 x 8-inch pan with foil, folding the excess over the sides to form handles. Grease the foil and set the pan aside.
Put the evaporated milk, marshmallow creme, butter, sugar, and salt in a large, heavy-bottomed saucepan. Bring to a boil over medium heat, stirring constantly with a heat-proof spatula. Scrape the bottom and sides of the pan often, as this mixture is apt to burn.
Once the mixture comes to a boil, cook for 5 minutes, stirring constantly; it will caramelize a bit, which is fine. Remove from the heat, add the chocolate and the vanilla, and stir until the chocolate is melted and the mixture is smooth. Add half of the nibs, stir to combine, and pour into the prepared pan. Top with the remaining nibs and allow to set.
Once the fudge is firm, lift it out of the pan using the foil handles and cut it into small squares with a long, sharp knife on a cutting board.