Place pumpkin and onions in pot covered with water bring to a boil, simmer till pumpkin is soft. Drain and combine with soup, sour cream and carrots. Mix bread with butter. Spread 1/2 in a 12x7x2 inch baking dish. Spread in veggie mix and sprinkle remaining bread stuffing on top. Bake at 350 degrees F. for 30 minutes.