Recipe courtesy of Ice Cream Ireland
Espresso Syrup
1/2 cup espresso (about 4 shots) (or 4 tablespoons espresso powder)
1 tablespoon sugar
Custard Base
5 egg yolks
1 cup sugar
1 1/8 cups whole milk
1/4 cup Kahlúa
1 1/8 cups heavy whipped cream, beaten until soft peaks form
2 oz. dark chocolate, shaved or chopped.
Reduce the espresso
In a small saucepan, heat the espresso and 1 tablespoon of sugar over medium high heat. Gently boil until reduced to 1/3 of original volume. Skip this step if using espresso powder.
Prepare the custard base
While the espresso is simmering, combine 1 cup of sugar with 5 egg yolks and beat until fluffy and color changes to light yellow. Scrape down sides of bowl with spatula at least once during mixing. In another saucepan, heat 1 1/8 cups of while milk until simmering. Do not boil. With mixer on medium speed, slowly pour the simmering milk into the beaten egg yolks and sugar mixture. Return this mixture to the saucepan and heat over medium heat, stirring constantly, until the mixture reaches 165 - 170 °F. Pour this mixture through a chinois or sieve and transfer to an ice bath or chill in the refrigerator. Wait until mixture has cooled before proceeding to the next step.
Shave or chop chocolate
Use a vegetable peeler to shave 2 ounces of chocolate into thin pieces. If you prefer to chop your chocolate, use a knife to chop into very small pieces. Frozen chocolate is very hard, so avoid the temptation to be generous with the size of the pieces. To remove excess powdery bits from chopped chocolate, you can swirl the chocolate chunks in a colander over the sink. While you are waiting for the custard base to chill, place an empty mixing bowl—to be used in the next step—in the refrigerator.
Finish the ice cream base and freeze
Add 1/4 cup of Kahlúa to the chilled custard base and stir until blended. Remove empty mixing bowl from refrigerator and pour in 1 1/8 cups of heavy cream. Beat on high speed until soft peaks form. Gently fold the whipped cream into the chilled custard base. Pour this mixture into your ice cream maker and freeze according to your maker's instructions. Once the ice cream starts to thicken just a little, you can pour in your shaved or chopped chocolate. Once ice cream is churned, transfer to a dedicated, odor-free container to ripen in the freezer.