Step 1

Whisk egg yolks to blend in medium metal bowl. Pour 1 cup cream into another medium bowl; set fine strainer over bowl with cream. Whisk milk, sugar, pinch of salt, and 1/2 cup cream in heavy medium saucepan; bring to simmer, stirring until sugar dissolves. Gradually whisk hot milk mixture into egg yolks. Return mixture to same saucepan and stir constantly over medium-low heat until custard thickens slightly and instant-read thermometer inserted into custard registers 160°F to 170°F (do not boil), about 5 minutes. Pour custard through strainer set over bowl with cream. Whisk mixture to blend; then whisk in rum and cinnamon. Chill custard until cold, about 2 hours.

Step 2

Process custard in ice cream maker according to manufacturer's instructions. Transfer ice cream to container. Cover; freeze until firm, at least 4 hours or overnight.