Bring a small pot of water to boil. Add sweet potato cubes and bring to a boil. Boil until tender and cooked through. Drain and mash until smooth. Set aside.

Spray a 2-quart round or 9-inch square baking dish with nonstick cooking spray. Place bread pieces into prepared dish. Dollop with mashed sweet potatoes and sprinkle with 1 cup marshmallows. Gently fold in a bit.

In a large bowl, whisk together eggs, milk, heavy cream, bourbon, brown sugar, cinnamon, vanilla extract and salt until well combined. Pour egg mixture over bread/potatoes in baking dish. Cover and refrigerate overnight to allow egg mixture to be absorbed.

Preheat oven to 350°F. Bake in preheated oven for 45-60 minutes or until center is set and no longer liquidy. If top begins to brown too quickly, place a piece of foil gently on top as a shield.

During last 10 minutes of baking, sprinkle remaining 1 cup marshmallows and chopped pecans on top. Continue baking until center is set, marshmallows are lightly browned and melted. Remove from oven and serve warm drizzled with maple syrup.