Heat the olive oil in a large saucepan over medium heat. Add the onion, celery, garlic and mushrooms and cover with lid. Cook on low heat for 5-6 minutes until onions have softened but not browned.
Remove 4 tablespoons of the mushrooms from the pan and set aside.
Pour the hot water into the pan and bring to the boil. Add the Knorr Vegetable Stock Pot. Turn the heat down to low and simmer for 15 minutes. Season with black pepper, remove from heat and puree in a blender until smooth.
Return blended soup to the saucepan, add the cream and heat gently.
Serve topped with the remaining mushrooms, divided between bowls and sprinkle with chopped parsley.