01 - Line an 8x8-inch baking pan with parchment paper, ensuring an overhang 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 simmer for 4 to 5 minutes, stirring constantly to prevent scorching.
04 - Remove saucepan from heat. Add white chocolate chips, ground nutmeg, ground cinnamon, and vanilla extract. Stir continuously until the mixture is completely smooth and the chocolate is melted.
05 - Immediately pour the fudge mixture into the prepared baking pan. Evenly smooth the surface with a spatula.
06 - Sprinkle the top with freshly grated nutmeg if desired.
07 - Let the fudge cool at room temperature for 30 minutes, then refrigerate for at least 2 hours or until firm.
08 - Lift the fudge from the pan by the parchment overhang and cut into 36 squares using a sharp knife.