Separate the eggs and place the yolks in a bowl. Use the whites for another recipe.
Add sugar to the yolks and use a whiskuntil pale and creamy.
Heat milk and cream in a saucepan and bring it to a gentle simmer. Now slowly whisk the milk mixture into the egg mixture. Make sure to add the milk mixture in a thin, steady stream so that you don't scramble the eggs. Keep whisking continuously till all the milk is whisked in.
Transfer the mixture back to the saucepan and continue to cook on medium heat till the eggnog thickens to your desired consistency stirring constantly.
Serve immediately or refrigerate for up to 3 days.