Maple Walnut Ice Cream

1. On small rimmed baking sheet, toast walnuts in 350°F (180°C) oven until golden and fragrant, about 5 minutes. Let cool and set aside.

2. In large heavy saucepan, bring maple syrup to boil over medium-high heat; boil until reduced to about 2/3 cup (150 mL), about 4 minutes. Remove from heat. Stir in 10% and whipping creams; heat over medium heat until tiny bubbles form around edge of pan.

3. In bowl, whisk egg yolks; slowly whisk in cream mixture. Return to pan; cook over medium-low heat, stirring constantly, until thick enough to coat back of spoon, 6 to 8 minutes.

4. Stir in maple extract. Strain custard into 9-inch (2.5 L) square metal cake pan. Place plastic wrap directly on surface; refrigerate until cold, about 1-1/2 hours.

5. Freeze until almost solid, 3 to 4 hours. Break into chunks and pur?in food processor until smooth. (Or freeze in ice-cream machine according to manufacturer's instructions.)

6. Spoon one-quarter of the ice cream into airtight container. Sprinkle with one-third of the walnuts, swirling slightly with spoon. Repeat twice. Cover with remaining ice cream. Freeze until firm, about 6 hours. (Make-ahead: Freeze for up to 1 week.)