Crumbly, buttery shortbread with a chewy, nutty topping spiked with lemon zest and herbs de Provence makes this recipe a decadent new addition to your holiday baking lineup.
Preheat the oven to 375°F. Line a 9 x 13-inch baking pan with parchment paper, allowing 1 inch of overhang on the long sides of the pan. Set aside.
In the bowl of a stand mixer fitted with the paddle attachment, add butter, granulated sugar, brown sugar, salt and vanilla. Turn to medium-high speed and mix until light and fluffy, about 3 minutes.
Turn mixter to low and add flour. Continue to mix until dough starts to sand, then increase speed to medium and continue to mix until dough comes together in clumps, another 1–2 minutes.
Firmly press dough into an even layer in the prepared pan, then prick surface of dough with a fork. Chill for 10 minutes in the refrigerator, then, bake for 18–20 minutes, or until shortbread is golden. Set pan on a cooling rack while you make the caramel nut topping.
Caramel Hazelnut Topping
Add butter, brown sugar, honey and salt to a small saucepan. With the stove set to medium high, bring the mixture to a low boil while continually whisking. Once bubbling, stir in the herbs de provence, lemon zest, and then slowly add in heavy cream and use a whisk to gently incorporate. Continue to boil for at least 2 minutes (or until color begins to lighten). Turn off heat and add in chopped hazelnuts, stirring to fully coat the hazelnuts with the caramel.
Pour hazelnut caramel over the shortbread and bake for 15–18 minutes, or until caramel is bubbling and deep brown in color. Allow to cool for several hours (preferably overnight) for caramel to set. Once cool, cut bars into small squares.