In a medium saucepan, heat the milk and heavy cream over medium-low heat. Bring to a gentle simmer, then remove from heat.
In a mixing bowl, whisk the egg yolks and sugar until thick and creamy.
Slowly pour a small amount of the hot milk mixture into the egg yolk mixture, whisking constantly to temper the eggs and prevent curdling.
Pour the egg mixture back into the saucepan with the rest of the milk. Cook over low heat, stirring constantly until the mixture thickens slightly and coats the back of a spoon (about 5 minutes).
Remove from heat and add the chocolate chips, stirring until fully melted and smooth. Stir in the vanilla extract, cinnamon, nutmeg, and cloves.
Garnishing: 6. Pour the chocolate eggnog into mugs and top with whipped cream or marshmallows. 7. Sprinkle with chocolate shavings or cocoa powder, and add a dash of nutmeg for aroma. 8. Garnish with a mini candy cane or chocolate curls for an extra festive look.

Serving Tip: Serve warm in holiday mugs and enjoy by the Christmas tree. This Christmas Eve Chocolate Eggnog will bring an extra dose of holiday cheer with every rich, chocolatey sip!