1 cup eggnog
3/4 cup + 3 tbsp heavy cream
3 tsp (1 1/2 packet) gelatin
1 cup cranberry juice or cocktail
sugar if needed
Put one inch of water in a shallow pan and bring to a simmer. Stir together the 2 tbsp gelatin and 3 tbsp of heavy cream together in a small bowl, and set in the shallow pan of simmering water to dissolve. Add eggnog to the gelatin mix and whisk. Let cool to room temperature.
Whip the 3/4 cup of heavy cream to soft peaks. Gently fold the cream into the eggnog base. It should be slightly foamy and creamy. Pour the cream into cups or bowls, and chill for at least an hour.
Dissolve 1 tbsp gelatin in hot juice. Add some sugar if needed. Let cool to room temperature, pour juice on top of the mousse in the cups or bowls. Chill till set.