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.
Bake for 20-25 minutes until a toothpick inserted in the middle comes out clean. Let cool in pan for 10 minutes before slicing.
Let cool slightly before slicing and serving.