Season inside of the kabocha with thyme, salt and pepper and rub with 4 tablespoons oil. Place onto a roasting pan flesh side up, and roast until caramelized and cooked through, about 25 minutes. Let cool slightly.
In a small saucepan combine the cream with the lemon grass and reduce by half. Strain into another small pan and hold warm.
In a medium pot over high heat, add 2 tablespoons oil. Add the carrots, onion and leek and cook until browned. Add the hot stock, reduce the heat to medium, and season, to taste.
When the squash is done, remove the cooked flesh from the squash and add to the pot. Transfer the contents of the pot, in batches, to a blender and blend until smooth. Strain through a fine sieve into a second pot and reduce until desired consistency is achieved. Season, to taste.
Serve soup in a warm soup bowl, and gently swirl in a dollop of the cream reduction. Garnish with chives.
A viewer or guest of the show, who may not be a professional cook, provided this recipe. It has not been tested for home use.