In a small bowl, combine the cinnamon and nutmeg. Reserve ¼ teaspoon for the topping and set aside.
Prepare a 9-inch square baking dish by lining with parchment paper. Set aside.
In a large saucepan, melt butter with sugar, eggnog, and salt over medium high heat. Bring to a boil. Stirring continuously until mixture reaches a rolling boil for four minutes. (Soft ball stage- 237 to 239 °F
Remove the mixture from heat. Using an electric mixer and mix with remaining ingredients on medium speed until smooth and white chocolate is completely melted .Pour into the prepared baking dish.
Sprinkle the remaining ¼ teaspoon of cinnamon and nutmeg over the fudge.
Place the fudge on an even surface for about 4 hours to set.
Use a warm, clean knife to slice the fudge for serving.
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