Pour the eggnog into a saucepan, then add the liqueur and stir well. Sprinkle the gelatine evenly over the top and leave it for 5 minutes to bloom.
Heat over low heat, stirring constantly for 2-3 minutes until the gelatine dissolves. Don't let it simmer or boil.
Pour the mixture into elegant glasses and allow to set in the fridge for 4 hours.
Top with your toppings and serve