Line a 9x13 baking dish with foil or parchment paper. This makes it easier to remove the fudge and cut it but is not necessary. This makes a full 9x13 pan of fudge so if you want shorter pieces you could use a bigger pan.
In a large heatproof bowl, add the chocolate chips, butter, nuts, marshmallow creme, vanilla, and salt. Set aside for later.
Pour sugar and evaporated milk in a large pot; it foams up a lot as it boils (at least 6 quart capacity). Bring mixture to a rolling boil over medium-high heat (foamy and light in color), THEN start a timer. Reduce heat to medium and boil 4 minutes, stirring constantly so it doesn't scorch. For firmer fudge, boil closer to 6 minutes, or cook to 234°F (soft-ball stage) on a candy thermometer.
Remove from heat and pour into the bowl containing the first mixture. Let it sit for a few minutes to melt, then stir until smooth and combined. Work quickly.
Spread in the pan. Cool at room temperature about 1 hour, then refrigerate until firm. Lift out and cut into squares.
Notes
Thermometer (optional): for more precision, cook to 234°F (soft-ball stage). This can take longer than 4 minutes.
Oily or dry fudge: usually overheated. Return it to a pot on low and stir in hot water 1 tablespoon at a time until smooth and glossy, then re-pan.
Didn't set: usually undercooked. Return it to the pot and bring back to a boil, adding a little evaporated milk if needed.
Storage: keep in an airtight container in the fridge up to two weeks. To freeze, wrap pieces well and freeze up to three months; thaw in the fridge.