Line a 9x13-inch baking dish with parchment paper or foil, leaving an overhang for easy removal. Lightly grease the lining to prevent sticking.
In a large saucepan over medium heat, combine the sugar, evaporated milk, and butter. Stir frequently until the butter melts and the sugar dissolves. Bring the mixture to a boil, stirring constantly.
4 & ½ cups granulated sugar, 12 oz evaporated milk, 1 cup unsalted butter
Once boiling, continue to stir constantly for about 9-10 minutes (or until the mixture reaches 234°F–240°F on a candy thermometer for soft-ball stage).
Remove from heat and quickly stir in the chocolate chips, and marshmallow creme until smooth and fully melted.
18 oz semi-sweet chocolate chips, 7 oz marshmallow creme
Stir in the vanilla extract and the chopped walnuts.
2 teaspoon vanilla extract, 1 ½ cups chopped walnuts
Immediately pour the fudge mixture into the prepared baking dish, smoothing the top with a spatula. You can top it with a few more walnut pieces for a beautiful finish.
Let the fudge cool completely at room temperature or refrigerate it until set. This could take about 2–3 hours.
Once the fudge is firm, lift it out of the pan using the overhanging parchment or foil. Cut into squares and enjoy your creamy, rich fudge!