5 ounces raw hazelnuts
1/2 cup (109 g) packed light brown sugar
2 1/2 cups (350 g) high-quality all-purpose gluten-free flour
1 teaspoon xanthan gum (omit if your blend already contains it)
1/2 teaspoon baking powder
1/2 teaspoon kosher salt
1 teaspoon ground cinnamon
16 tablespoons (224 g) unsalted butter, at room temperature
1 extra-large egg (60 g unshelled)
1 teaspoon pure vanilla extract
confectioners’ sugar, for dustring
seedless raspberry jam
Roast the hazelnuts. Preheat your oven to 350°F and set aside a clean tea towel. Place hazelnuts in a single layer on a rimmed baking sheet, and place in the center of the preheated oven. Roast for 10 minutes, or until fragrant. Remove the hazelnuts from the oven and place them immediately in the center of the tea towel, cover the hazelnuts with the towel and rub vigorously from the outside of the towel to remove the skins of the hazelnuts. Place the peeled and roasted hazelnuts in the bowl of a food processor fitted with the steel blade and pulse until finely ground (stopping short of creating a paste). Add the brown sugar, and pulse again until well combined, and set aside. Lower the oven temperature to 325°F.
Make the cookie dough. In a large bowl, place the flour, xanthan gum, baking powder, salt and cinnamon and whisk to combine well. Add the ground hazelnut and brown sugar mixture, then the butter, egg and vanilla, mixing to combine after each addition. The dough should come together and be soft but thick. Divide the dough into two equal portions, cover one portion in plastic wrap and set it aside. Place the remaining portion between two sheets of unbleached parchment paper, and roll into a rectangle a bit less than ¼ inch thick. Place the rolled out dough, still covered in parchment, on a flat surface and place it in the freezer until firm (about 10 minutes). Repeat with the second piece of dough.
Cut out the cookies. Remove the first piece of rolled out dough from the freezer when firm, and cut out 24 rounds of dough with a 1 ½ inch cookie cutter. Place the rounds 1 inch apart on a rimmed baking sheet lined with unbleached parchment paper. Remove the second piece of rolled out dough from the freezer when firm and cut out 24 more rounds of dough with a 1 ½ inch cookie cutter. Place the rounds 1 inch apart on a rimmed baking sheet lined with unbleached parchment paper. From these 24 rounds, cut out and remove a small shape from the very center of the dough (here I used a small star cutter).
Bake the cookies. Place the first baking sheet in the center of the preheated oven and bake, rotating once, until lightly golden brown (about 10 minutes). Remove from the oven and allow the cookies to cool until firm on the baking sheet and transfer to a wire rack to cool completely. Place the second baking sheet in the center of the preheated oven and bake, rotating once, until lightly golden brown (about 9 minutes for the cookies with the center shapes cut out). These are the tops of the cookies. Remove from the oven and allow the cookies to cool until firm on the baking sheet and transfer to a wire rack to cool completely.
Assemble. Once the cookies are completely cooled, place the cookie tops (with the cutout centers) face up on a clean sheet of parchment paper. Sprinkle evenly with confectioners’ sugar. On a separate sheet of parchment paper, lay out the whole, bottom cookies, face down, and place 1 teaspoon of jam on the underside of each cookie, spreading the jam into an even layer. Top with the sugared cookies. Do not use much pressure in assembling the cookies or the tops will break.