1. Peel and de-knob the artichokes and as you peel them, cut them into rough chunks and place them in a bowl of cold salted water to prevent them from discolouring. Then, scrape the carrots and slice them into largish chunks. 2. Melt the butter in a large saucepan, soften the onion and celery in it for 5 minutes, keeping the heat fairly low. Drain the artichokes and add them to the pan, along with the carrots. Add some salt and keeping the heat very low, put a lid on and let the vegetables sweat for 10 minutes to release their juices. 3. Pour in the hot stock, stir well, put the lid back on and simmer very gently for a further 20 minutes, or until the vegetables are soft. 4. Liquidise the soup in tow batches, then return to the pan, taste to check the seasoning and reheat very gently until it just comes to simmering point. 5. Serve in hot soup bowls, each garnished with a swirl of creme fraiche and a few leaves of parsley.