Beat eggs, sugar, and salt in large heavy saucepan until blended. Stir in 2 cups milk. Cook over low heat, stirring constantly but gently, until mixture is just thick enough to just coat a metal spoon with a thin film and temperature reaches 160°F, about 15 minutes. Do not allow to boil. Remove from heat immediately. Stir in remaining 2 cups milk and vanilla. Refrigerate, covered, until thoroughly chilled, several hours or overnight. Garnish with a sprinkle of ground nutmeg, cinnamon sticks, or candy canes and whipped cream.