Heat heavy cream in a saucepan until just boiling. Pour over chocolate chips and let sit for one minute. Stir until smooth.

Mix in eggnog, nutmeg, and vanilla extract until thoroughly combined.

Chill the mixture covered in the refrigerator for about 2 hours or until firm.

Scoop out portions using a melon baller and roll into balls.

Roll each truffle in cocoa powder until fully coated.

Serve immediately or store in an airtight container in the fridge for up to one week.