In a bowl, whisk together ground hazelnuts, ground almonds, powdered sugar, ground cinnamon, and a pinch of salt.
Add the lemon juice, and water. Knead with your hands (or use a food processor) to form a sticky cookie dough.
Form the dough to a disc, wrap tightly in cling film and refrigerate for 1 hour, or until firm enough to work with.
Preheat oven to 400 °F (200 °C).
On a piece of cling film, roll out the dough to be about ¼-inch (0,6 cm) thick.
Use a star cookie cutter to cut out cookies. Transfer them to a baking sheet lined with parchment paper.
Bake for about 6-8 minutes, or until slightly crisp on the edges.
Once the cookies are done baking, allow to cool completely before adding the glaze.
In a measuring cup, stir together the powdered sugar, lemon juice and water to form a thick paste.
Brush the cookies with the glaze and allow it to harden. Dust with powdered sugar or sprinkle with a pinch of cinnamon as desired and enjoy!
