Place the potatoes in a large pot, and fill with enough lightly salted water to cover. Bring to a boil, and cook until tender, about 10 minutes. Drain, mash with 1/4 cup of butter, and set aside.
In a large bowl, mix together the bread, onions, savory, salt and pepper. Stir in the mashed potatoes, while drizzling in the remaining butter. The mixture should become the texture of biscuit dough. Stuff turkey just before roasting. Place any leftover stuffing in a bowl in the refrigerator for later.