Begin by roasting the hazelnuts in a dry pan over medium heat until fragrant, about 5-7 minutes. Let them cool slightly before using.

In a blender, combine the roasted hazelnuts, shallots, parsley, salt, and pepper. Blend until the mixture becomes smooth and creamy, requiring about 1-2 minutes.

In a large pot, add the blended mix with water or stock. Whisk together until well incorporated, ensuring there are no lumps left behind.

Place the pot over medium heat and bring the mixture to a gentle simmer. Allow it to cook for 15-20 minutes, stirring occasionally, until the soup thickens and flavors meld beautifully.

Adjust the consistency by adding more liquid if necessary. Serve the soup warm, garnished with freshly chopped parsley.