1. Brush Jerusalem artichokes well under cold running water and remove tough ends if necessary. Place in a saucepan and cover with water. Bring to a boil; reduce heat to medium, and simmer for 20 minutes or until artichokes are tender. Drain. Let cool and then peel.
2. Melt butter over medium-low heat in the same saucepan. Add the leeks and sauté until softened about 2-3 minutes without allowing them to brown. Incorporate the Jerusalem artichokes and chicken broth. Bring to a boil and simmer for about 5 minutes to reheat artichokes.
3. Blend mixture in a food processor. Stir in the cream. Add chicken broth for a more liquidy consistency. Season with salt to taste.
4. To toast the hazelnuts, heat a small non-stick skillet over medium heat. Add hazelnuts and stir gently for 1 minute or until fragrant and lightly browned.
5. Spoon into bowls. Garnish with toasted hazelnuts and chervil.

CHEF'S SECRET:

Peeling Jerusalem artichokes is not an easy task! Here are three options:

1. Peel them after cooking, as indicated in the recipe.
2. Peel them raw, before cooking. If you choose this option, it is important to immediately plunge them into water with lemon juice because the flesh turns black when exposed to air. Use a paring knife to cut off the peel or a spoon to scrape it off.
3. Don't peel them! Jerusalem artichoke peel is edible, but it will colour the soup and small pieces will be visible. Not to worry. The soup will be every bit as delicious.