In a heavy saucepan, bring cream and milk to a bare simmer. Stir in vanilla bean and seeds, cover, and let steep for one hour. Remove the bean, wash away dairy, and set aside to dry. The used bean can be added to a 2 cups of sugar to make vanilla sugar.
Whisk together egg yolks and sugar in a bowl until well-combined and light in color. Slowly pour yolk mixture into dairy mixture, whisking well to combine. Cook custard on low heat, whisking frequently, until it thickens, coating the back of a spoon but leaving a clean line when swiped with a finger.
Strain into an airtight container, then stir in vanilla extract and Scotch. Add salt and chill overnight, then churn using an ice-cream maker according to manufacturer's instructions.
Eat immediately as soft-serve or let firm up in freezer for two to three hours.
Making Ice Cream Without A Machine
Prepare your ice cream mixture, then chill it over an ice bath.
Put a deep baking dish, or bowl made of plastic, stainless steel or something durable in the freezer, and pour your mixture into it.
After forty-five minutes, open the door and check it.
As it starts to freeze near the edges, remove it from the freezer and stir it vigorously with a spatula or whisk. Really beat it up and break up any frozen sections. Return to freezer.
Continue to check the mixture every 30 minutes, stirring vigorously as it’s freezing using a spatula or a sturdy whisk along with some modest physical effort. If you have one, you can use a hand-held mixer.
*Keep checking periodically and stirring while it freezes (by hand or with the electric mixer) until the ice cream is frozen. It will likely take 2-3 hours to be ready.