An easy way to add flavor to homemade vanilla ice cream is to stir in ground cinnamon.
Combine half-and-half and whipping cream in a stainless steel saucepan. Cook over medium heat just until mixture begins to boil.
Whisk together yolks and next 3 ingredients in a large bowl. Gradually whisk hot cream mixture into yolk mixture, and pour back into saucepan.
Cook over low heat (do not boil), stirring constantly, until custard begins to thicken and coats back of a spoon. Strain into a metal bowl; place bowl in an ice-water bath. Cool completely, stirring occasionally.
Pour mixture into freezer container of a 5-quart hand-turned or electric freezer. Freeze according to manufacturer's instructions.