Preheat the oven to 400 degrees Fahrenheit. Line a baking sheet with Gefen Parchment Paper.

Drizzle the parsnip pieces with olive oil. Place the parsnips on the baking sheet. Roast in the oven for 45 minutes, until soft and lightly browned. Transfer the parsnips to the slow cooker insert.

While the parsnips are roasting, peel and dice the Jerusalem artichokes. Place the pieces in a bowl of cold water with the lemon juice to keep them artichokes from turning dark.

Preheat a slow cooker to low.

Place a small sauté pan over medium-high heat. Lightly coat the bottom of the pan with olive oil. Sauté the shallots until they are slightly browned and soft. Add the garlic and cook for two minutes more. Add the wine to the pan and cook the mixture for three minutes. Add the wine-shallot mixture to the slow cooker insert. Drain the Jerusalem artichoke pieces and add them to the insert. Add the thyme and chicken stock to the insert.

Cover and cook on low for five hours, until the Jerusalem artichokes and parsnips are very soft.

Puree the soup in batches or with an immersion blender until the soup is very creamy. Season with salt and pepper.

Ladle the soup into bowls and garnish with chopped toasted hazelnuts and a drizzle of toasted hazelnut oil.