01 - Line an 8x8-inch baking pan with parchment paper, ensuring there is an overhang on two sides for easy removal.
02 - In a medium saucepan set over medium heat, combine unsalted butter, eggnog, and granulated sugar. Stir frequently until mixture reaches a gentle boil.
03 - Reduce heat to low and simmer the mixture for 4 to 5 minutes, stirring continuously.
04 - Remove the saucepan from the heat. Add white chocolate chips, ground nutmeg, ground cinnamon, and pure vanilla extract. Stir until the chocolate is fully melted and mixture is smooth.
05 - Pour the fudge mixture immediately into the lined pan, spreading evenly with a spatula.
06 - Sprinkle evenly with freshly grated nutmeg, if desired.
07 - Allow the fudge to cool at room temperature for 30 minutes, then refrigerate for a minimum of 2 hours or until firm.
08 - Using the parchment paper overhang, lift the fudge from the pan. Cut into 36 squares with a sharp knife.