1. Pierce the sweet potatoes all over with a fork and wrap them in foil. Bake in a 400°F oven for 1.5 hours. Carefully remove from the oven and allow to cool completely before unwrapping and slicing in half. Reduce the oven temperature to 275°F.
2. Scoop out the sweet potato flesh and place it in a blender with the milk. Blend until smooth.
3. In a heavy pan, heat the sweet potato and milk mixture over medium heat. Add the cornmeal, and, while you stir it with a whisk, bring to a boil. Reduce the heat to low-medium and continue to whisk as you cook for 5-10 minutes, until thickened. Remove from the heat.
4. Add the butter, brown sugar, molasses, spices, and salt. Whisk to blend all the ingredients. Let the mixture cool slightly.
5. In a separate small bowl, beat the eggs. Add about 1/2 cup of the warm cornmeal mixture to the eggs and beat again. Add the tempered eggs to the larger pot of the batter and whisk together to combine.
6. Add the 1/2 cup of cream, half and half, sour cream or creme fraiche and whisk again.
7. Pour the batter into a buttered baking dish and bake at 275°F for 2 hours. Serve warm, alone or with cream or whipped cream, crème fraîche, or ice cream.