Start this recipe by roasting half of the pumpkin in the oven at 200`c, drizzled with a little olive oil and seasoned with salt and pepper. When ready, remove from the oven and blitz to a puree. Put aside. Cut the remaining pumpkin into small cubes and put aside. In a heavy-based saucepan sweat the onion in the remaining oil until soft but not browned. Add the chopped sage and cook for a couple more minutes. Add in the Arborio rice and mix well for a few seconds to coat the grains with oil, then pour in one-third of the stock and bring to a gentle simmer. Cook until almost all the stock is absorbed. Add the pumpkin cubes to the risotto and the remaining stock and continue to simmer gently until the stock is absorbed and the pumpkin is soft. The texture of the risotto should be loose and creamy. When the risotto is ready stir in the pureed pumpkin along with the butter, grated cheese and chopped parsley. Serve immediately into deep bowls.