1. Coat the inside of a 10-inch cast iron skillet with 1/2 tbsp oil. Place it in the oven and begin to preheat the oven to 425°F.
2. In a large bowl, stir together the cornmeal, flour, sugar, baking powder, salt, cinnamon, and nutmeg until well mixed.
3. Mash the sweet potatoes until fairly smooth. Transfer 1.5 cups of the mashed potatoes to a large bowl. Add the sour cream, milk, and 2 Tbsp oil, and whisk until combined. Add the eggs and whisk until combined again.
4. Pour the sweet potato mixture into the bowl with the dry ingredients. Stir the two together just until combined and no dry mix remains on the bottom of the bowl. It's okay if the mixture is a little lumpy, just be sure not to over mix.
5. Carefully take the hot skillet out of the preheated oven and scoop the batter into it. Smooth the top out until it's even, then return it to the oven.
6. Bake for 22-25 minutes, or until the center is puffed, the top is golden brown, and it's slightly cracked around the edges. Remove from the oven, cut into eight pieces, and serve. Preferably with butter.

Total Cost: $4.00 recipe / $0.50 serving