2 ¼ cup whole milk
1 ¼ cup heavy cream
¾ cup sugar
6 egg yolk
pinch of salt
6 Tbsp unsweetened cocoa powder
1 Tbsp Frangelico or other hazelnut liqueur
2 tsp vanilla extract
Heat the oven to 350° and toast the hazelnuts on a baking sheet until deep golden brown, about 15 minutes. When cool, finely grind 2 cups of the nuts in a food processor. Chop the remaining 1 cup of nuts and set them aside.
Put the milk and cream into a saucepan and bring to a simmer over medium heat. Remove the pan from the heat, stir in the finely ground hazelnuts, and steep for 1 hour. Strain through a fine-mesh sieve into another saucepan, pressing on the solids before discarding them. Add 1/2 cup of the sugar to the milk. Bring to a simmer over medium heat, stirring until the sugar dissolves.
Put the yolks, salt, and the remaining 1/4 cup of sugar into a medium mixing bowl and whisk together until thick and pale yellow. Whisk in the cocoa. Gradually ladle about 1 cup of the hot milk into the yolks, whisking constantly. Stir the warm yolk mixture into the hot milk in the saucepan. Reduce the heat to low, and cook, stirring constantly, until the custard is thick enough to coat the back of the spoon and registers between 175° and 180° on an instant--read thermometer, 3-5 minutes.
Strain the custard into a medium bowl. Add the liqueur and vanilla and stir frequently until cooled. Cover and refrigerate until completely chilled, about 4 hours. This will keep in the refrigerator for up to 2 days.
Churn the custard in an ice cream maker following the manufacturer’s directions. Just before the gelato has finished churning, add the reserved chopped hazelnuts, letting the paddle stir them in. Transfer the gelato to a quart container with a lid. Cover and freeze for a couple of hours or until it is just firm.
Recipe courtesy of Canal House Cooking Volume No. 7: La Dolce Vita by Melissa Hamilton & Christopher Hirsheimer/Andrews McMeel Publishing, 2012.