Preparation

Toss onion with olive oil in a baking dish. Cover with foil. Roast at 350°F (175°C), stirring occasionally, for about 30 minutes or until starting to soften. Remove foil and continue to roast until golden-brown and very soft. Transfer onions to a saucepan with mushroom stock, balsamic vinegar, thyme, and rosemary. Simmer for about 15 minutes, stirring occasionally. Purée in a blender until smooth and strain through a fine mesh strainer. Stir in Madeira. Season with salt and pepper. To make Chive Cream: Blend all ingredients in a blender until smooth. (If you’ve just made the soup, you can use the blender right away without washing it.) Season with salt and pepper. To cook the mushrooms: Sauté mushrooms in olive oil with remaining ingredients over moderate heat until nicely browned, seasoning with salt and pepper. Using a nonstick pan will eliminate the need for excessive oil. To serve, reheat soup and mushrooms if necessary. Ladle soup into heated bowls and spoon cream into the middle. Scatter mushrooms over. Sprinkle with chives and parsley sprigs for garnish.