In large bowl or pot, stir together half & half, vanilla, and 2 cups of milk. Set aside.
Separate eggs, placing the yolks in a large microwavable bowl and the whites in a mixer bowl.
Beat egg yolks slightly and add 1 cup of the milk. Mix well. Cook in microwave for 2 minutes on high. Stir, and continue microwaving in 30 second intervals, stirring each time, until the mixture thickens. (Or reaches a temperature of 160°F on a food thermometer.) You may need to shorten the time between intervals to avoid cooking the egg, which will result in lumpy eggnog.
When the egg custard has thickened, stir in the salt and ½ cup sugar. Stir until the sugar dissolves. Pour into the milk mixture and stir.
Meanwhile, beat egg whites until foamy. Add ¼ cup sugar and continue beating until white form soft peaks. Fold into the eggnog mixture, then whip with a wire whisk.
Chill in refrigerator 3 hours. To serve, pour into a serving bowl, dot with whipped cream and sprinkle with nutmeg.