Preheat the oven to 400 degrees Fahrenheit. Roast the sweet potato for about 35 - 45 minutes or until tender and cooked through. Remove from the oven and let it cool for a few minutes.
Remove all the pulp from the sweet potato and mash it until smooth. Reserve.
Coat the inside of a 10-inch cast iron skillet with oil. Place the skillet in the oven and preheat to 425 degrees Fahrenheit.
While the oven and skillet are preheating, stir together the cornmeal, flour, sugar, baking powder and salt in a large bowl.
In a separate bowl, whisk together 1 ½ cup of the mashed sweet potato, eggs, sour cream, milk and 2 tablespoons of oil until smooth.
Stir the wet ingredients into the dry ingredients and mix to combine. Add the diced jalapenos, sliced green onions and ½ cup of shredded cheese. Fold gently until well incorporated.
Take the preheated skillet from the oven and carefully pour in the cornbread batter. Smooth the top and return the skillet to the oven.
Bake for about 20 to 25 minutes or until the top is golden, carefully remove from the oven and top with the remaining cheese. Return to the oven and bake for a few minutes until the cheese melts.
Remove from the oven and serve.