Blueberry-Cinnamon Swirl Ice Cream

Sprinkle gelatin over water in a small bowl; let stand, stirring once or twice, while you make the base for the ice cream.

Pour 1 1/2 cups milk into a large saucepan. Cut vanilla bean in half lengthwise; scrape the seeds into the milk and add the pod.

Heat the milk mixture over medium heat until steaming. Whisk egg yolks and condensed milk in a medium bowl. Gradually pour in the hot milk, whisking until blended. Return the mixture to the pan and cook over medium heat, stirring with a wooden spoon, until the back of the spoon is lightly coated, 3 to 5 minutes. Do not bring to a boil or the custard will curdle.

Strain the custard through a fine-mesh sieve into a clean large bowl. Add the softened gelatin and whisk until melted. Whisk in the remaining 1 1/2 cups milk. Cover and refrigerate until chilled, at least 2 hours.

Whisk the ice cream mixture and pour into the canister of an ice cream maker. Freeze according to manufacturer's directions. During the last 5 minutes of freezing, add blueberries and cinnamon to the ice cream maker. If necessary, place the ice cream in the freezer to firm up before serving.