1 cup maple syrup
2 cups heavy cream
1 cup whole milk
1/4 teaspoon salt
2 large eggs
1/3 cup walnuts, toasted and chopped
Special equipment: an ice-cream maker
Boil syrup in a 2-quart heavy saucepan over moderately high heat until reduced to 3/4 cup, 5 to 10 minutes.
Stir in cream, milk, and salt and bring to a boil over moderate heat.
Whisk eggs in a large bowl, then add hot cream in a slow stream, whisking.
Transfer to saucepan and cook over moderately low heat, stirring constantly, until slightly thickened and an instant-read thermometer registers 170°F, 1 to 2 minutes (do not let boil).
Pour custard through a fine sieve into a clean metal bowl, then cool, stirring occasionally. Chill, covered, until cold, at least 3 hours.
Freeze custard in ice-cream maker until soft-frozen, then, with motor running, add nuts. Continue churning ice cream until frozen, then transfer to an airtight container and put in freezer to harden.
·To cool custard quickly after straining, set bowl in a larger bowl of ice and cold water and stir until chilled. ·Custard can be chilled up to 24 hours.