Place into a saucepan milk, cream, cinnamon, vanilla bean, vanilla seeds, and nutmeg.
Bring to the boil over a medium heat.
Once boiling, remove from the heat.
Allow the ingredients to steep whilst cooling.
In a large bowl, beat egg yolks and sugar until combined.
Slowly whisk in the milk and mix until smooth.
Add bourbon or rum.
Stir.
Refrigerate overnight or for up to 3 days.
Before serving, beat the egg whites in a large bowl until soft peaks form.
Fold into eggnog until combined. Serve and garnish with freshly grated nutmeg.