Preheat oven to 200°C.
Toss diced parsnips with olive oil, maple syrup, salt and pepper. Spread on a baking sheet and roast for 20–25 minutes until tender and caramelised.
In a large pot, heat the remaining olive oil and vegan butter over medium heat.
Add onion, celery and leek with a pinch of salt and pepper. Sauté until soft and translucent.
Add garlic, chestnuts, thyme and the roasted parsnips. Cook for 2–3 minutes, stirring occasionally.
Pour in the vegetable broth and bring to a boil. Reduce heat and simmer for 15–20 minutes.
Blend the soup until completely smooth, adding more broth if needed to reach desired consistency.
Stir in nutmeg and vegan crème fraîche. Adjust seasoning to taste and warm through gently.
Serve in warm bowls with a drizzle of truffle oil and fresh thyme sprigs.