Diane Morgan demonstrates how to make a delicious soup using porcini mushrooms. Start by sautéing a big batch of chopped onions and leeks in butter until they are nicely cooked. Then mix in the chopped mushrooms and some flour and cook for a few minutes until the flour is absorbed. Add in some stock, some bay leaves, fresh thyme leaves, salt and sugar (sugar brings out the flavors in the soup). Simmer for about ten minutes, remove the bay leaves, and it's ready to go into the blender. Use an immersion blender to puree the soup right in the pan. Finally, stir in the cream, and serve it with some parmesan-herb croutons.