In a heavy saucepan, whisk eggs, sugar and salt. Gradually add 4 cups of the milk. Cook and stir fairly frequently over low heat until temperature reaches 165°. This can take 30-35 minutes. Do not allow to boil. Immediately transfer to a large bowl.
Stir in vanilla, nutmeg and remaining milk.
Place bowl in an ice-water bath, stirring until milk mixture is cool. If mixture separates, you can process it in a blender or food processor until smooth.
Refrigerate, covered, until cold, about 3-4 hours.
When ready to serve, beat the heavy cream until soft peaks form. Whisk the whipped cream gently into the cooled milk mixture. If desired, sprinkle with additional nutmeg before serving.