Place the white chocolate in a large bowl and place over simmering water to melt.
In a small saucepan whisk the egg yolks with the sugar until smooth.
Whisk in the heavy cream, cinnamon, nutmeg and brandy.
Place the saucepan over low heat and continuously stir until the mixture begins to thicken.
Pour the mixture through a strainer into the melted white chocolate and stir until smooth.
If the mixture is still warm place in the refrigerator for a few minutes.
Fold 1/2 of the whipped cream into the eggnog base until there are no visible streaks of cream. Place in a pastry bag.