1. Clean and roughly chop all of the mushrooms. (The smaller you cut them, the faster they will cook.)
2. Prepare a "mushroom mirepoix": In a large sauce pot on medium-high heat, warm about 3 tablespoons of olive oil. Throw chopped mushrooms into the pot with the minced garlic and whole sprigs of fresh thyme.
3. Sauté the mushrooms until tender and smaller in size. Then, deglaze the pan with the Marsala by scraping up all of the fond from the bottom; allow the Marsala to reduce.
4. After several minutes, add all of the chicken stock; bring to a simmer and reduce for about 30 minutes. (The longer you let it simmer, the more intense the flavors become.)
5. Now, allow the soup to cool. Remove the thyme stems and transfer to a blender. Cover the top for safety, and blend to your desired consistency. (We like it velvety smooth.) BE CAREFUL as even warm soup can splatter and cause accidents.
6. Return the blended soup to the soup pot and bring to medium heat. Add the cream and warm to serve. Garnish with leaves of fresh thyme.