Gently melt the white chocolate in a double boiler or microwave in 15-second intervals, stirring until smooth. Let cool slightly.

In a mixing bowl, stir the softened cream cheese until smooth. Add the slightly cooled white chocolate and mix until fully incorporated.

Slowly pour in the eggnog while mixing. Stir in the vanilla extract, nutmeg, cinnamon, and a pinch of salt. If using, mix in the bourbon or rum.

Cover the bowl and refrigerate for at least 4 hours or overnight until the mixture is firm enough to scoop.

Use a small cookie scoop or spoon to portion the filling into 1-inch balls. Roll gently between your hands to smooth. Place the truffles on a parchment-lined tray and return to the fridge for about 30 minutes.

While the truffles are chilling, melt the dark chocolate using the same method as the white chocolate. Let it cool slightly.

Dip each chilled truffle into the melted dark chocolate using a fork or dipping tool, allowing the excess to drip off. Place each one back onto the parchment-lined tray.

If desired, drizzle with melted white chocolate and sprinkle with crushed gingersnaps or a pinch of nutmeg before the coating sets.

Allow the truffles to set completely at room temperature or refrigerate until firm. Store in an airtight container in the fridge for up to one week.