01 - Line an 8x8-inch baking pan with parchment paper, allowing an overhang on the sides for easy removal.
02 - In a medium saucepan over medium heat, combine unsalted butter, eggnog, and granulated sugar. Stir frequently until the mixture reaches a gentle boil.
03 - Reduce heat to low and continue to simmer for 4 to 5 minutes, stirring constantly to prevent scorching.
04 - Remove saucepan from heat. Immediately add white chocolate chips, ground nutmeg, ground cinnamon, and pure vanilla extract. Stir thoroughly until the chocolate melts and the mixture is smooth.
05 - Pour the fudge mixture into the prepared pan and smooth the surface with a spatula.
06 - Sprinkle the top evenly with freshly grated nutmeg, if desired.
07 - Allow the pan to cool at room temperature for 30 minutes. Transfer to the refrigerator for at least 2 hours or until completely firm.
08 - Using the parchment paper overhang, lift the fudge out of the pan. Cut into 36 equal pieces with a sharp knife.