Preheat the oven to 350 degrees. Clean and slice sweet potatoes lengthwise in half. Place in dish, cover and bake for 30-40 minutes (depending on size) or until you can stick a fork in them easily.
While the sweet potatoes are baking- mix the walnuts and agave together in a small bowl.
Remove sweet potatoes from oven and top with maple /walnut mixture and then place back in the oven uncovered for about 15 minutes.
Remove from oven and lightly sprinkle with cinnamon if desired. You can also sprinkle with cayenne pepper if you like a little zip. Serve and enjoy warm.