Place ice cream maker base into freezer at least 24 hours prior to churning, if not kept in the freezer at all times.
Place ice cream storage container that you'll be storing ice cream in, in freezer. Fill medium bowl with ice and water. Nest smaller bowl inside, and place fine strainer on top of small bowl. Combine heavy cream, milk, sugar and salt in medium pot.
In separate small bowl, whisk eggs; set aside. Cook milk mixture over medium low heat until mixture is steaming, with small bubbles around edge of pan. Do not boil!
While whisking constantly, slowly pour about half of the hot cream mixture into bowl with eggs to slowly raise the temperature of the eggs without cooking them.
Slowly pour all of egg mixture into pot and replace over medium low heat.
Continue cooking and stirring until mixture thickens, and reaches 165° with digital thermometer. (see tips below) Pour mixture through strainer, into small bowl over ice bath.
Gently stir mixture to help heat escape and cool quickly.
Add flavoring of choice - vanilla, extracts, oils, etc.
Secure lid and refrigerate for 24 hours.
20-30 minutes prior to churning, place custard base in freezer. (This aids in creamier ice cream)
Set ice cream machine to 25 minutes and begin churning. Machine must be on and moving before you add the custard.Slowly pour in custard base. Churn until thick like soft serve ice cream. Pour/scoop ice cream into chilled ice cream storage container.
Serve immediately for soft-serve, or place in freezer for firmer scoops of ice cream.