Line two baking sheets with parchment paper and set aside.
In the bowl of a stand mixer or large bowl with hand held mixer, beat the eggs whites on high until very stiff. They should be so stiff that they pull away from each other when sliced with a knife.
Add the sifted icing sugar and lemon extract and beat on high until mixture is stiff, holds its shape like stiffly whipped cream and does not move when picked up with a spoon. Remove 3 tablespoons of this mixture into a small bowl and set aside.
Gently fold in the finely ground hazelnuts until evenly incorporated. Drop approximately 1 tablespoon sized mounds onto the parchment lined baking sheets. The cookies can be spaced close together as they should not spread. Add approximately 1/4 teaspoon of the egg white/icing sugar mixture on top of each cookie and gently press one whole hazelnut on top (pointed side up). Let the cookies dry at room temperature until they are dull and dry to the touch.
Preheat the oven to 325 degrees F. Bake the cookies for 10 minutes or until golden brown on the bottom. Let cool completely before removing from the baking sheets.
Store in an air tight container. These cookies also freeze well.