01 - Preheat oven to 350°F. Line two baking sheets with parchment paper and set aside.
02 - In a medium bowl, whisk together the gluten-free flour, cocoa powder, baking soda, and salt until evenly distributed.
03 - In a large bowl, beat the softened butter, brown sugar, and granulated sugar with an electric mixer on medium speed until light and fluffy, about 2 minutes.
04 - Add the eggs one at a time, beating well after each addition. Mix in the vanilla extract and espresso powder until fully incorporated and the mixture is smooth.
05 - Gradually add the dry ingredient mixture to the wet ingredients, mixing on low speed just until combined. Avoid overmixing to keep the cookies tender.
06 - Gently fold in the chocolate chips and chopped toasted hazelnuts using a spatula until evenly distributed throughout the dough.
07 - Scoop tablespoon-sized portions of dough onto the prepared baking sheets, spacing them about 2 inches apart to allow for spreading.
08 - Bake for 10 to 12 minutes, until the edges are set but the centers remain slightly soft and underbaked for a chewy texture.
09 - Allow the cookies to cool on the baking sheets for 5 minutes, then transfer to a wire cooling rack to cool completely before serving.