Spinach and Button Mushroom Soup

Wash and sort the spinach. Remove any hard stalks and roughly chop the leaves. Blanch briefly in boiling, salted water. Refresh in cold water and drain. Peel and finely chop the onions and garlic. Heat 2 tbsp butter and sweat the onions and garlic until translucent. Clean and roughly chop the mushrooms. Reserve 8 tbsp of the mushrooms to put into the soup at the end. Add the remaining mushrooms to the pan with the onions and garlic and saute over a high heat until all the liquid has evaporated. Heat the remaining butter and saute the reserved mushrooms over a high heat. Season with salt and pepper. Stir the sherry into the mushrooms and onions and add the vegetable stock. Simmer without a lid for 5 minutes, then add the cream and creme fraiche.