Preheat your oven to 325°F (165°C). Remove the innards from the turkey, rinse it with cold water, and pat dry with paper towels.
In a large skillet, melt 1 cup of butter over medium heat. Add the chopped onions and celery, sautéing until softened (about 5-7 minutes).
In a large mixing bowl, combine the bread cubes, sautéed vegetables, chicken broth, sage, thyme, salt, and pepper. Mix thoroughly to create the stuffing.
Stuff the turkey cavity with the prepared stuffing. Place any remaining stuffing in a separate baking dish.
Rub the remaining butter over the turkey skin and season with additional salt and pepper. Place the turkey in a roasting pan, breast side up.
Roast in the preheated oven for about 3 hours, approximately 13-15 minutes per pound, or until the internal temperature reaches 165°F (74°C). Baste occasionally with pan juices.
About 30 minutes before the turkey is done, place the additional stuffing in the oven to cook until golden brown.
For the mashed potatoes, peel and chop the potatoes. Boil in a pot of salted water until tender (about 15-20 minutes). Drain and return to the pot.
Add milk and sour cream to the potatoes and mash until creamy and smooth. Season with salt to taste.
To prepare the cranberry sauce, combine the cranberries, sugar, and water in a saucepan. Bring to a boil and simmer for about 10-15 minutes until the cranberries burst and the sauce thickens.
Allow the turkey to rest for 20 minutes before carving. Serve with stuffing, mashed potatoes, and cranberry sauce.