01 - Line an 8x8-inch baking pan with parchment paper, leaving some overhang for easy removal.
02 - In a medium saucepan over medium heat, add unsalted butter, eggnog, and granulated sugar. Stir frequently until the mixture reaches a gentle boil.
03 - Reduce heat to low and simmer the mixture for 4 to 5 minutes, stirring constantly to prevent scorching.
04 - Remove saucepan from heat. Add white chocolate chips, ground nutmeg, ground cinnamon, and pure vanilla extract. Stir until chocolate is fully melted and mixture is smooth.
05 - Immediately pour the fudge mixture into the prepared baking pan. Smooth the top evenly with a spatula.
06 - Sprinkle freshly grated nutmeg evenly over the top, if desired.
07 - Allow to cool at room temperature for 30 minutes, then refrigerate for at least 2 hours or until firm.
08 - Lift the fudge out using the parchment overhang and cut into 36 squares with a sharp knife.