How to Make It
Preheat the oven to 300°. Spread the cashews and sesame seeds on a rimmed baking sheet and bake for 12 to 15 minutes, until lightly golden. Let cool.
Line a large rimmed baking sheet with a silicone baking mat or parchment paper and lightly coat the parchment with nonstick cooking spray.
In a small bowl, whisk the vanilla bean paste with the salt, baking soda and nutmeg.
In a large saucepan, bring the sugar, water and corn syrup to a boil. Cook over moderately high heat, brushing down the side of the pan with a wet pastry brush, until the syrup reaches 250° on a candy thermometer, 10 minutes. Off the heat, whisk in the butter.
Bring the syrup back to a boil and cook over moderately high heat, stirring, until golden brown, 5 to 7 minutes. Remove from the heat and stir in the vanilla bean mixture, then the cashews and sesame seeds. Immediately scrape the brittle onto the prepared baking sheet and, working quickly, spread it in an even layer with an offset spatula. Lay another silicone baking mat or a sheet of sprayed parchment over the brittle and use a rolling pin to even it out. Remove the top baking mat and let the brittle cool completely, about 1 hour. Break the brittle into pieces before serving, storing or gifting.
Vanilla bean paste (vanilla bean seeds in sugar syrup) is available at baking supply stores and from nielsenmassey.com.