Place chicken broth, parsnips, 5 celery stalks, celery root, white onion, ½ fennel bulb, and 8 garlic cloves in a large pot over medium heat. Bring to boil. 

Lower to a simmer and cook for 45 minutes. Strain, reserving cooked parsnips and celery root.

Split pearl onions from root down. Heat a small, heavy-bottomed frying pan over medium-high. Add 2 to 3 teaspoons of canola or grapeseed oil. Place onions cut side down. Season with salt. Cook for 5 to 7 minutes, or until nice char has developed on the cut side. Set aside.

In a separate large pot, heat 1 tablespoon evoo over medium heat. Add sweet onion, carrot, and remaining 3 celery stalks, 6 garlic cloves, and ½ fennel. Sauté for 6 minutes.

Add dry white wine; continue to cook for 3 to 5 minutes until liquid is reduces. Add chestnuts, nutmeg, and strained broth. Simmer for 10 minutes. 

Transfer soup to a food processor or blender, and puree until very smooth. If texture is too thin, add some of the reserved cooked celery root and parsnip to add texture, until creamy and smooth. Season with salt and pepper. 

Garnish with charred pearl onions and serve a piece of breaded fried chicken skin topped with parsnip puree.