Preheat oven to 400℉ and place cast iron skillet inside to heat. This step hels form a nice crust on the bottom of the cornbread.
In a large bowl, whisk together the cornmeal, flour, salt, baking powder, and baking soda.
In a separate bowl, whisk together the milk, buttermilk and the eggs. Then whisk in the melted butter.
Add the egg mixture to the flour mixture and stir to combine. Add the corn kernels, jalapeños and 1 cup of the cheese. Stir.
Carefully remove the hot skillet from the oven. Reduce oven temperature to 375℉. Coat the bottom and sides of the hot skillet with cooking spray.
Pour the batter and sprinkle with the remaining cheese. Place the skillet and place the skillet in the center of the oven. Bake until center is firm and a cake tester or toothpick comes out clean, about 20-22 minutes.