In a medium saucepan, warm the milk, 2 cups of the pumpkin eggnog, sugar, and salt. Use a paring knife and scrape all the vanilla seeds into the warm milk, then add the pod as well. Cover, remove from the heat , and let steep at room temperature for 1 hour.
3
Remove the vanilla bean halves (rinse and reserve them for another use).
4
In a separate medium bowl, whisk together the egg yolks. Slowly pour one cup of the warm pumpkin eggnog mixture into the egg yolks, whisking constantly, then scrape the warmed egg yolks back into the saucepan.
5
Stir the mixture constantly over medium heat whit a heatproof spatula, scraping the bottom as you stir, until the mixture thickens and coats the spatula. Mix in the vanilla or rum and stir over an ice bath until cool.
6
Chill the mixture thoroughly in the refrigerator, then freeze it in your ice cream maker according to the manufacturer's instructions.