Walnut Toffee with Vanilla: A Methodical Guide to Caramelized Nuts

Preheat oven to 160°C (325°F). Spread walnuts on a baking sheet and toast for 8-10 minutes until fragrant. Keep warm in the oven until ready to use.

Line a large baking sheet with parchment paper or a silicone mat. Place the toasted walnuts in an even layer on the sheet.

In a heavy-bottomed saucepan, combine sugar, corn syrup, water, and the scraped vanilla bean pod (reserve seeds). Stir gently to moisten sugar. Bring to a boil over medium-high heat, then stop stirring. Clip on a candy thermometer.

When the syrup reaches 120°C (250°F) (firm-ball stage), add the cubed butter and vanilla seeds. Stir carefully; the mixture will bubble vigorously. Continue cooking without stirring.

Cook until the thermometer reads 150°C (300°F) (hard-crack stage). Immediately remove from heat and stir in baking soda (the mixture will foam). Remove the vanilla bean pod.

Quickly pour the hot toffee over the walnuts, tilting the sheet to spread evenly. If desired, sprinkle flaky sea salt on top. Let cool undisturbed for at least 30 minutes.

Once fully set, break the toffee into irregular pieces by hand or with a knife. Store in an airtight container at cool room temperature for up to 2 weeks.