Pick nettles in your garden or in the woods with gloves on, taking the youngest leaves from the top (the nettle heads), and avoiding nettles already in bloom.
Shake the nettles to dislodge insects, wash them in cold water and cut the leaves. Wring out the nettles.
Cut the cloves of garlic, and crush the hazelnuts coarsely.
In a medium blender, put half of the nettles, half of the olive oil and squeeze lemon juice on top. Blend on high speed.
Add the other leaves, the rest of the oil and a little lemon juice. Blend again.
Then add the Parmesan cheese, garlic, pine nuts and hazelnuts and mix, still on high speed.
Taste to adjust the seasoning (add a little parmesan or lemon juice if you wish) and add pepper. If the consistency is not creamy enough, you can add a little liquid (oil, lemon juice, or a little water).
Once the right consistency is obtained and the pesto is seasoned to your taste, put it in a glass jar and cover it with a layer of olive oil so that it does not blacken, especially if you do not eat it within 2 days.