Heat the oven to medium high heat and butter a baking dish.
Cut the apples and the pumpkin to large cubes. Take the pits out of the prunes.
In a food processor, grind prunes, butter, rosemary, walnuts and cinnamon (if using), salt, pepper and 1/4 of pumpkin and apple cubes.
Carefully separate the skin from the meat and rub the prunes mixture under the skin. If you have some mixture left, stuff the chicken with it along with some of the apples and pumpkin cubes. Put the rest of the pumpkin and apples in the baking dish and place the chicken on them.
Soak a baking paper in water and drain it. Cover the chicken with it, so the chicken skin wont burn, and put the dish in the oven. Cook for an hour and a half or until the chicken is done. Serve hot!