Preheat your oven to 450 degrees. Place your cast iron skillet in the oven as the oven is preheating.
Combine buttermilk, sour cream, creamed corn, and egg in a large bowl and mix well. Mix in shredded cheese and green chiles.
Add cornmeal, sugar, and salt to the cornbread mixture and fold to combine. Set mixture aside.
Once the oven is preheated, carefully remove your cast iron skillet. It will be HOT!
Carefully pour your favorite oil into the skillet, and use a brush to brush the oil up the sides to coat the pan. Avocado oil is recommended. There should be a small amount of oil in the bottom of the pan, about 1/8 - 1/4" (enough to fry the crust of the cornbread).
Place the oiled skillet back into the oven for about 2-3 minutes to heat the oil. Then, carefully remove the cast iron skillet. The pan and oil will be VERY hot, so be careful!
Spoon your cornbread batter into the cast iron skillet. You will notice the batter starts to fry immediately. The skillet should be about 2/3 full of batter.
Place in oven, and cook until a knife inserted in the center of the cornbread comes out clean.
Carefully remove the cast iron skillet cornbread from the oven, and allow to cool before serving.