01 - Line an 8x8-inch baking pan with parchment paper, ensuring an overhang for easy removal.
02 - In a medium saucepan over medium heat, blend butter, eggnog, and sugar, stirring frequently until the mixture reaches a gentle boil.
03 - Reduce heat to low and simmer for 4 to 5 minutes, stirring continually to prevent scorching.
04 - Remove saucepan from heat. Add white chocolate chips, nutmeg, cinnamon, and vanilla extract. Stir thoroughly until chocolate is completely melted and the mixture is smooth.
05 - Immediately pour the fudge into the prepared pan, smoothing the surface with a spatula.
06 - If desired, sprinkle freshly grated nutmeg evenly over the top.
07 - Allow fudge to cool at room temperature for 30 minutes, then refrigerate for at least 2 hours until set and firm.
08 - Lift fudge from pan using the parchment overhang. Cut into 36 squares with a sharp knife.