01 - Line an 8x8-inch baking pan with parchment paper, leaving an overhang for easy removal.
02 - In a medium saucepan 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 for 4 to 5 minutes, stirring constantly.
04 - Remove from heat and add white chocolate chips, ground nutmeg, ground cinnamon, and vanilla extract. Stir until chocolate is completely melted and mixture becomes smooth.
05 - Immediately 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 fudge to cool at room temperature for 30 minutes, then refrigerate for at least 2 hours until firm.
08 - Lift fudge from the pan using the parchment overhang and cut into 36 squares with a sharp knife.