Put the chicken in a large saucepan with 2.25 litres(79 fl oz/9 cups) of cold water and bring to the boil. Skim the surface well, then add the carrot, leek, garlic, parsley, thyme and peppercorns and season with salt. Bring back to the boil, skimming off any more froth that comes to the surface. Lower the heat, cover the pan and simmer for about an hour.
Strain the broth into a clean pan. (You won’t need any of the solids here, but some chicken can be picked off and the vegetables can be chopped up, turned through some rice and served with parmesan.)
Peel and deseed the pumpkin, then cut it up into smallish pieces. You should have about 750 g(1 lb10 oz). Heat the butter in a large non-stick frying pan and sauté the pumpkin over fairly high heat so that it turns quite golden in places and starts to get a little soft inside. Tip it into the broth and simmer over low heat for about 20 minutes until it is soft all the way through. Purée with a hand-held blender until it is completely smooth, and taste for salt. Add the cream, whisking it in a bit, and heat through, or swirl a little cream through each bowl. Serve with some brown bread and butter, and adults could add a small scattering of ground chilli powder if they want.