Preheat oven to 350 degrees F and line a baking sheet with foil.

Pierce sweet potatoes a few times with a fork and place on prepared baking sheet. Bake for 55 to 65 minutes, until sweet potatoes are tender when pierced with a fork or sharp knife. Let sweet potatoes cool slightly, then slice open lengthwise and spread open slightly. Mash pulp of each sweet potato with a fork.

Combine chopped walnuts, cranberries, butter, brown sugar, cinnamon, and salt in a medium bowl; mix well.

Mound each sweet potato with ⅓ cup cranberry-walnut mixture. Place sweet potatoes back in oven and bake an additional 15 minutes, until topping is warm and fragrant. Remove sweet potatoes from oven, drizzle with maple syrup, and serve warm.