In a medium bowl whisk the egg yolks, sugar, cinnamon, nutmeg, and salt.
In a saucepan over medium heat, add the milk, vanilla extract, rum extract, and 1 cup of heavy cream. Cook until just starting to boil.
Carefully pour the hot milk over the egg yolk mixture while whisking the yolks constantly. Once all of the milk is added, pour everything back into the saucepan and cook, stirring occasionally, over medium heat for about 5 minutes, or until a thermometer reaches 165°F.
In a medium bowl add the remaining 1 cup of heavy whipping cream and use an electric mixer to beat until stiff peaks form. About 2 minutes. Fold the whipped cream into the eggnog.
You can serve the eggnog warm or allow to cool in the fridge before serving. Sprinkle with cinnamon or top with whipped cream, if desired. Eggnog stays fresh in the fridge for 1 week. For delicious spiked eggnog add your favorite brandy, rum, or whisky.