Shred porcinis into pea-sized pieces and place in a small bowl. Cover with cold water and stand while you start on the soup.

Heat butter in a large stockpot. Add onion and leeks. Cook stirring until translucent and lightly browned. Add button mushrooms and stir well. When slightly browned, add stock and bring to the boil, then add potatoes.

The poricinis should be soft now and can be added to the soup, along with the water they were soaking in. Note: there may be some sediment (sand and dust) sitting at the bottom of the soaking water, so just pour it in gently into the pot discarding any 'murky' water.

Cook until the potatoes are soft (20 minutes). Add milk and cook for further 5 minutes. Season with salt and pepper. Using a soup ladle, smash the potatoes gently ensuring that some cubes retain their shape. Turn off the heat and allow to cool slightly before serving.

To make cheesy herb bread simply mix cheese and herbs in a small bowl, layer on bread and grill until the cheese melts.