01 - Preheat oven to 350°F. Line a baking sheet with parchment paper and set aside.
02 - In a medium bowl, whisk together the almond flour, coconut flour, baking powder, and sea salt. Fold in the chopped roasted hazelnuts until evenly distributed.
03 - In a large bowl, beat the softened butter and granulated sweetener using an electric mixer until light and fluffy, approximately 2 minutes.
04 - Add the egg, maple extract, and vanilla extract to the butter mixture. Beat until fully combined and smooth.
05 - Gradually add the dry ingredient mixture to the wet ingredients, mixing on low speed until a cohesive dough forms and no dry pockets remain.
06 - Scoop tablespoon-sized portions of dough onto the prepared baking sheet, spacing them 2 inches apart. Flatten each portion slightly with the palm of your hand.
07 - Sprinkle the tops of each cookie with additional chopped hazelnuts and a pinch of flaky sea salt, if desired.
08 - Bake for 12 to 15 minutes, or until the edges are golden brown and the centers appear set.
09 - Allow cookies to cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely before serving.