In a large pot, heat the oil, and sauté the chopped onion and sliced leek for about 3 minutes.
Next, add washed and sliced mushrooms and fry for another 10 minutes stirring now and then. Add the carrot, parsnip and potato. Mix well and cook for 3-4 minutes. Season with salt and pepper.
Pour in the hot vegetable stock and bring to the boil. Simmer, covered for about 15 minutes. until the vegetables are soft.
Mix with a hand blender until smooth, add cream at the end and serve.