Combine milk, 1 cup heavy cream, sugar, Kosher salt, and cinnamon stick in a medium saucepan, then stir. Bring to a boil over medium heat.
Cook, stirring occasionally until the rice is tender. Once you remove it from the heat, it will stop cooking.
Whisk egg yolks. Slowly pour in the hot milk mixture while whisking to temper the egg. Pour the egg mixture into the saucepan with the rice, stirring very well.
Stir in vanilla extract. Transfer to a serving bowl (or a mixing bowl), then serve warm with cinnamon sprinkled on top.
If serving cold, we recommend stirring in milk to create a looser texture.