Ingredients

• 2 cups hazelnuts (8 ounces), toasted , skins rubbed off, and cooled
• 3/4 cup sugar
• 1/8 teaspoon salt
• 4 1/2 cups whole milk
• 3 tablespoons cornstarch
• 4 ounces bittersweet chocolate (no more than 60% cacao), finely chopped
• Equipment: an ice cream maker

Instructions

1. Pulse hazelnuts with sugar and salt in a food processor until finely ground. Transfer to a heavy medium saucepan with milk and bring just to a boil, stirring occasionally. Remove from heat and let steep, covered, 20 minutes.
2. Strain mixture through a fine-mesh sieve into a bowl, then return to cleaned saucepan.
3. Put 1/4 cup milk mixture in a small bowl and whisk in cornstarch. Return to saucepan, then boil over medium heat 2 minutes, whisking often (mixture will be thick). Remove from heat and add chocolate, stirring until melted and incorporated. Chill, stirring occasionally, until very cold, 3 to 6 hours.
4. Freeze mixture in ice cream maker. Transfer to an airtight container and put in freezer to firm up.