In a sauce pan, combine sugar and egg yolks. Beat until smooth and light yellow in color. Add salt and stir in milk. Cook over medium heat, stirring constantly, until mixture bubbles and thickens enough to coat the back of a spoon. Remove from heat then stir in vanilla. Place custard in a refrigerator container then stir in spirits. Place lid on container and refrigerate until cool- 3 to 4 hours. Just before serving, whip cream into peaks. Fill clear glasses with eggnog and top with dollop of cream. Dust with nutmeg.