Juice the oranges so the volume reaches 1 ¼ cups of liquid; set aside.
In a medium saucepan over medium heat, combine cream, milk, sugar and salt. Stir until sugar is completely dissolved.
In a small bowl, whisk the egg yolks until light and pale.
Temper the eggs by very slowly pouring in about ¼ cup of the hot milk mixture, whisking continuously.
Pour the egg mixture into the saucepan and whisk until very well blended. Reduce the heat to medium-low and cook for about 5 minutes, stirring constantly, making sure the mixture DOESN’T boil.
Remove from the heat and let it cool to room temperature.
About 30 minutes later, add orange juice and Cointreau if you're using it. Stir well, transfer to a large measuring cup and let it sit for another 15 minutes.
Cover with plastic wrap and transfer to the refrigerator overnight.
The next day, pour the mixture into an ice cream maker and churn according to the manufacturer's directions, about 15 to 20 minutes.
Spoon ice cream into a container and transfer to the freezer for at least 4 hours.