Saute the chopped onion, carrot and celery in 1-2 tablespoos of butter until very soft. Remove from pan.
Add the chopped sage, rosemary and salt and pepper to taste.
Coat the turkey necks with olive oil, salt and pepper them and roast them at 400 degrees for about 45 min, until meat it soft enough to pick off the bones.
Saute the liver and/or gizzards in the fat used for the mirepoix until well cooked. Once cool, chopped the meat finely and add it to the mirepoix.
Pick the meat from the turkey necks and chop finely, and add to the mirepoix and giblets.
Mix the chopped vegetables and meats together and place them as a bottom layer in a roasting pan, 9x17x2.
Heat the broth to simmering and then add a quart of it to the cubed bread in a large bowl. Cover and let sit 5-10 minutes. If the bread cubes loose their shape and amass, you have added enough broth. If not, add more and repeat the steps. The bread cubes and liquid should form a mass that is almost spreadable.
Melt remaining butter (about 4 oz) and add to the broth and bread mixture. Add salt and pepper to taste.
Layer bread mixture above the chopped vegetable and meat layer, spreading to cover completely.
Bake at 375 degrees for about an hour, until bread layer is slightly crispy on top but slightly moist underneath.