Pre-heat oven to 375°F. Slice the bread into 1 1/2-2 inch cubes and place in a large mixing bowl. Melt 4 tablespoons of butter and pour it over the bread. Gently, using your hands, mix the bread and butter so all the cubes are lightly coated. Place bread on a baking sheet (it is ok if bread overlaps) and bake for for 3 minutes. Gently stir and bake for an additional 3-4 minutes. The bread should be toasted and lightly crisped. Set aside.
While bread toasts prepare the sweet potatoes. Peel the sweet potato and cut into 1 inch pieces. Place in a bowl and toss with olive oil, salt, pepper, and cinnamon. Place on a baking sheet and into oven when bread finishes toasting. The oven temperature will remain the same. Roast for 15 minutes, stirring at the halfway point.
In a dutch oven (or another oven and stove top safe baking dish), melt 2 tablespoons of butter over medium heat. Add, celery, onion, garlic, and fresh herbs. Saute until the onions are celery begin to soften.
Remove sweet potatoes from the oven and reduce heat to 350°F. Add toasted bread to dutch oven and stir. Add white wine to dutch oven and stir. Add chicken broth and sweet potatoes to dutch oven and gently stir. Season with additional salt and pepper if necessary.
Cover and bake for 15 minutes until heater through.
This recipe can be prepared 2 days in advance and heated in the oven. Baking time will be long if it is chilled.