Step 1

Bring a kettle to the boil, then pour the water over the dried porcini just to cover. Heat half the butter in a saucepan, then gently sizzle the onion, garlic and thyme for 5 mins until softened and starting to brown. Drain the porcini, reserving the juice, then add to the onion with the mixed wild mushrooms. Leave to cook for 5 mins until they go limp.

Step 2

Pour over the stock and the reserved juices, bring to the boil, then simmer for 20 mins. Stir in crème fraîche, then simmer for a few mins more. Blitz the soup with a hand blender or liquidiser, pass through a fine sieve, then set aside.

Step 3

Heat the remaining butter in a frying pan, fry the bread cubes until golden, then drain on kitchen paper. To serve, heat the soup and froth up with a hand blender, if you like. Ladle the soup into bowls, scatter over the croûtons and chives and drizzle with truffle oil.