In a small bowl, stir together the herb bouquet ingredients. Pour the herbs into a small voile or cheesecloth bag and tie tightly. Set aside.

In a large stockpot, melt the butter and add the onions. Saute on medium heat for about 8 minutes or until the onions are translucent and beginning to brown. Stir in the sherry and saute until the sherry is reduced and the pan is almost dry.

Stir the chicken broth, herb bouquet, and chestnuts into the stockpot. Bring to simmer and cover. Cook for 20 minutes and then remove the herb bouquet. Move the pot off the heat.

Using an immersion blender, blend the soup until it's smooth and creamy. Stir in the cream, salt, and nutmeg. Reheat the soup and check the seasonings. Serve in bowls with a dash of fresh parsley and a drizzle of pure maple syrup.