Combine the cream, milk, sugar, vanilla and cinnamon in a heavy saucepan, and cook, stirring occasionally, over medium-low heat until the sugar has dissolved and the mixture is hot. Remove the pan from heat.
Whisk the egg yolks in a bowl. Very slowly add 1 cup of the hot mixture, whisking constantly. When the egg mixture has warmed, whisk it slowly back to the hot cream mixture in the saucepan. Place the saucepan over medium heat, and stir constantly until the mixture thickens, 10 to 15 minutes; do not boil.
Remove from heat and allow to cool to room temperature, and then refrigerate it, loosely covered, until chilled (preferably overnight, but at least 8 hours).
Pour into an ice cream freezer machine and follow the manufacturer's instructions.
Notes
*You can substitute half & half cream for the heavy whipping cream, but then be sure to use whole milk.
*Use good, fresh cinnamon! Buy a new jar- it will make a difference.
*As with any ice cream recipe, it will turn out best if you can freeze the container at least 24 hours ahead. The ice cream base works best if it is chilled for 8 or more hours.