1) Grease a 9" square cake pan with parchment; grease the parchment. Or lightly grease your favorite bake-and-give pans; we like the mini round pans.
2) Combine the sugar, corn syrup, cream, butter, salt, eggnog flavor, and nutmeg in a deep, narrow (6- to 8-quart) heavy-bottomed pot.
3) Bring the mixture to a boil over medium-high heat, stirring until smooth — the sugar should have dissolved, with no grittiness in the bottom of the pan.
4) Boil until the mixture reaches 235°F to 240°F on a candy or digital thermometer, about 15 to 20 minutes.
5) Remove the pot from the heat and add the chocolate a handful at a time, stirring until smooth. Note: As soon as the chocolate has melted, stop stirring! If you continue to stir, it'll separate and become grainy.
6) Pour the mixture into the parchment-lined pan — you'll want to do this fairly quickly, as once it starts to cool, the fudge will be much harder to pour.
7) Cool the fudge overnight, until firm. If it's in a large pan, cut it into serving-size pieces. Wrap airtight, and store at room temperature for several days.
Yield: about 64 pieces; or 6 mini round pans.