In a medium saucepan set over medium heat, combine the sugar with the butter and milk. Stir or whisk until it begins to boil, then continue mixing it while it boils. Once it begins to “foam”, let it continue to boil for about 3-4 minutes. Remove the pan from the stove, and add in the chips and marshmallow creme. Quickly stir the mixture until the chips have melted with the creme. Using a rubber spatula, or wooden spoon, add the rum and the nuts into the fudge mixture and gently stir it in to combine it all together.
3 cups granulated sugar, ¾ cup salted butter, 5 ounces evaporated milk, 12 ounces white chocolate chips, 7 ounces marshmallow creme, ¼ cup spiced rum, ½ cup chopped walnuts