Prepare and measure all ingredients before beginning as this is a quick process.
Line 8×8 pan with wax paper or foil.
In pot over medium heat, combine the sugar, evaporated milk, butter and salt. Bring to a boil while stirring constantly. Continue to boil and stir for 5 minutes. Remove from heat.
Stir in 2 cups marshmallows, chocolate chips and vanilla. Stir quickly until melted and smooth.
Stir in walnuts then quickly fold in remaining mini marshmallows. Transfer mixture to prepared pan. Refrigerate 2+ hours or until firm.
Lift wax paper and entire fudge block to remove from pan. Transfer to cutting board, peel off paper and cut into squares. Store in airtight container in the refrigerator.
Notes
Be sure to boil the mixture the full amount of time to ensure the fudge sets properly.Ingredients can affect the outcome quite a bit. I exclusively use Nestle Semi-Sweet Morsels, Carnation Evaporated Milk and Jet Puffed Mini Marshmallows.