Wash and clean cauliflower and tore it into florets. Cut the leeks into rings. In a saucepan of heated olive oil saute the vegetables until soft. Pour over with 1 liter of cold water and add the vegetable broth. Season them with salt, pepper and a pinch of nutmeg. Once the cauliflower is cooked, add the semolina. Stir continuously until the moment that is cooked. Pull the soup from the heat and let cool slightly. Add the cream and the butter and blend the soup. Serve portion of the hot soup with lemon juice.