Place oil in a 10 inch cast iron skillet. Using a paper towel, spread the oil out over the bottom and sides of the pan. Place in the oven and preheat to 400 F.
In a large bowl, combine the flour, cornmeal, sugar, baking powder and salt.
Whisk in the buttermilk, butter, and eggs. Fold in 1 cup of the cheese, the corn and the diced jalapenos.
Remove the skillet from the oven. Pour in the batter and spread out evenly.
Top the batter with the remaining cheese and add the sliced jalapenos.Pour batter in pan, top with sliced jalapeños and remaining 1/2 cup cheese, and place in the oven. Bake for 20-25 minutes until a toothpick inserted in the middle comes out clean. Let cool in pan for 10 minutes before slicing.
Bake for 20-25 minutes or until golden brown and a toothpick inserted into the center comes out clean.