Sweet potatoes are one of those "superfoods" supplying amazing amounts of nutritional value. 214% of your daily requirement of Vitamin A, 50% of Vitamin C, along with magnesium, and many other trace elements. Not all sweet potatoes are orange inside, as a matter of fact, you can find purple ones. Alongside sweet potatoes in the grocery aisle are garnet potatoes, and what is commonly called a yam, although it is not a true yam. Any of these can easily be used in this recipe. Even pumpkin or butternut squash could be substituted. Adjust your cooking time accordingly.