Place a 9 or 10-inch cast iron skillet on the middle rack in the oven, and preheat to 400°F.
In a large bowl, whisk together the cornmeal, flour, sugar, baking powder, and salt.
In a medium bowl, whisk together the milk, eggs, butter, and cream-style corn.
Add the wet ingredients to the dry ingredients and stir together until well combined. Fold in the shredded cheese and jalapenos until just combined.
Carefully remove the hot cast iron skillet form the oven and add the oil or butter to grease the skillet.
Pour the batter into the skillet, and bake for 20-25 minutes, until lightly browned and a toothpick inserted in the center comes out clean. Let cool for 10 minutes before serving.
Notes
To make in a 12-count muffin tin: Preheat oven to 375°F and spray the inside of each well with cooking spray, grease with oil, or line with cupcake liners. Make the batter as instructed above, then pour it evenly into each well. Bake for 15 minutes, or until a toothpick inserted into the center comes out clean.