Line a 9x9-inch baking pan with foil. Lightly spray or butter; set aside.
In a medium heavy-bottomed sauce pan set over medium heat, combine the marshmallow creme, sugar, evaporated milk, butter, and salt. Stir frequently, until to allow the sugar to dissolve.
Bring the mixture to a boil, stirring constantly for 4-5 minutes.
Remove from the heat and stir in chocolate chips until melted, then add the nuts and vanilla, stir to combine. Pour into the prepared baking pan, place in the refrigerator for 1 hour before cutting into squares.
I find that at high altitude I only need to boil the mixture for 4 minutes instead of 5. However, my mother-in-law lives at sea level and she boils the mixture for the full 5 minutes.