Toast Pine Nuts: Toast the pinon pine nuts in a dry skillet over medium heat, stirring frequently, until golden brown and fragrant. Let cool completely.
Make the Custard Base: In a saucepan, combine the heavy cream, whole milk, sugar, salt, and vanilla bean (if using). Heat over medium heat, stirring until the sugar dissolves and the mixture just begins to simmer.
Whisk Egg Yolks: In a mixing bowl, whisk the egg yolks until light and frothy.
Temper the Egg Yolks: Slowly pour a small amount of the hot cream mixture into the egg yolks, whisking constantly to temper the eggs. This prevents them from scrambling.
Combine and Cook: Pour the tempered egg yolk mixture back into the saucepan with the remaining cream mixture. Cook over low heat, stirring constantly, until the custard thickens enough to coat the back of a spoon (about 5-7 minutes). Do not boil.
Strain and Chill: Strain the custard through a fine-mesh sieve into a clean bowl. Stir in the vanilla extract (if not using a vanilla bean). Cover the bowl with plastic wrap, pressing it directly onto the surface of the custard to prevent a skin from forming. Refrigerate for at least 4 hours, or preferably overnight, to chill completely.
Churn: Pour the chilled custard into your ice cream maker and churn according to the manufacturer's instructions.
Add Pine Nuts: During the last few minutes of churning, add the toasted pinon pine nuts.
Freeze: Transfer the ice cream to a storage container and freeze for at least 2 hours to harden completely.
Serve and Enjoy: Let the ice cream soften slightly before serving.