• Combine the heavy cream, whole milk, ½ cup of the sugar, espresso powder, and kosher salt in a medium saucepan. Heat over medium-low heat, stirring frequently to dissolve the sugar and espresso powder, until the mixture is steaming and reaches 160–165°F. Do not allow the mixture to simmer or exceed 170°F. Remove the saucepan from the heat.

  While the cream mixture is warming, place the egg yolks and remaining ¼ cup sugar in a medium bowl. Whisk until completely combined and the mixture looks smooth and slightly lighter in color.

  While whisking the yolks constantly, slowly drizzle in about 1 cup of the warm cream mixture. Begin with a very small stream so the yolks warm gradually without scrambling.

  Pour the tempered yolk mixture back into the saucepan with the remaining cream mixture. Return the saucepan to low heat and cook, stirring constantly with a silicone spatula or wooden spoon. Scrape along the bottom and into the corners of the saucepan as you stir so the custard cooks evenly.

  Cook until the custard thickens slightly and reaches 170–175°F. It should lightly coat the back of the spoon or spatula, and a finger drawn through the custard should leave a clear path. Do not allow the custard to boil or exceed 180°F.

  Immediately remove the saucepan from the heat and stir in the vanilla extract. Pour the custard through a fine-mesh strainer into a clean bowl or container.

  Cover and refrigerate for at least 4 hours, preferably overnight, until the custard is thoroughly chilled. The custard should be 40°F or colder before it is churned.

  Pour the chilled custard into the frozen bowl of a 1½-quart ice cream maker. Churn according to the manufacturer’s directions, usually 20–25 minutes, or until the ice cream is thick and has the consistency of soft serve.

  Transfer the ice cream to a freezer-safe container. Cover and freeze for 3–4 hours, or until firm enough to scoop.

Notes

• Three tablespoons of espresso powder gives this ice cream a bold coffee flavor. For a milder flavor, reduce the espresso powder to 2 tablespoons.

  Do not judge the coffee flavor while the custard is warm. Chilling and freezing mute flavors, so the cold custard and finished ice cream will taste less intense.

  For the smoothest texture, make sure both the custard and the ice cream maker bowl are thoroughly chilled before churning