Line a cookie sheet with parchment paper and set aside.
In a medium mixing bowl, add the softened cream cheese, powdered sugar, cinnamon, nutmeg, and rum extract. Use an electric mixer on medium speed to blend until completely smooth and well combined. Set aside.
In a microwave-safe bowl, combine ⅔ cup of the white chocolate melts and the eggnog. Microwave at 50% power for one minute. Remove from the microwave and stir until the mixture is completely melted and smooth. If needed, microwave for an additional 20-30 seconds until fully melted.
Fold the melted chocolate mixture into the cream cheese mixture until well combined.
Place the bowl in the freezer for 15 minutes to make the truffle dough easier to handle.
Roll the chilled truffle dough into 1-inch balls and place them on the parchment-lined cookie sheet. Refrigerate for 15 minutes to allow the truffles to harden slightly.
Melt the remaining white chocolate melts in the microwave at 50% power for one minute, or longer if necessary. Stir until completely melted.
Dip each truffle ball into the melted white chocolate, coating it evenly, and place it back on the lined cookie sheet. Immediately sprinkle a bit of ground nutmeg on top of each truffle.
Chill the truffles for 30 minutes to allow the white chocolate coating to harden completely.
Storage: Store the truffles in an airtight container in the refrigerator for up to one week.