Preheat oven to 375 degrees and pour bacon drippings in a 10 inch cast iron skillet. In a large bowl; whisk together the sweet potato, cinnamon, vanilla, eggs, buttermilk and sugar {set aside}. Mix cornmeal, flour, salt, baking soda and baking powder until combined. Next add the chilled butter to the cornmeal and pulse until coarse and crumbled. Add the cornmeal mixture to the sweet potato mixture and stir. Pour into prepare skillet and bake for 40-45 minutes. Let cool, slice and serve with lots of salted butter! YUM!