1 1/2 cups heavy cream
1 1/2 cups milk
1 cup dulce de leche
4 duck egg yolks (or 6 chicken egg yolks)
1/2 cup sugar
1 teaspoon pure vanilla extract
Pinch of salt
Optional: Toasted hazelnuts, chopped
In a saucepan over medium heat, warm the cream, milk and 2/3 cup of the dulce de leche, stirring constantly, until the mixture is blended and steam begins to rise from the surface, 4 to 5 minutes.
In a heatproof mixing bowl, whisk together the egg yolks, sugar and salt until blended. Slowly stream in the hot cream mixture, whisking constantly until fully incorporated. Pour mixture into a clean saucepan and set over medium-low heat. Cook, whisking continuously until the custard thickens and a finger drawn across the back of a spoon leaves a path, 8 to 10 minutes; do not allow the custard to boil. Stir in vanilla extract.
Pour the custard through a fine-mesh sieve set over a clean bowl. Nestle the bowl in a larger one filled halfway with ice and water and cool the custard to room temperature, stirring occasionally. Refrigerate until chilled, at least 1 hour.
Transfer the custard to an ice cream maker and freeze according to the manufacturer’s instructions. At the end of the freezing stage, drizzle the remaining 1/3 cup dulce de leche and toasted hazelbuts into the churning ice cream until just swirled throughout.
Transfer the ice cream to a container, cover and freeze until firm, 3 to 4 hours. Makes about 1 quart.
SOURCE: Adapted from Williams-Sonoma Kitchen.