Step 1Heat the oven to 325 degrees. Butter or spray a 13-by-9-inch pan. Place the all-purpose flour, cake flour, sugar, cornmeal, baking powder and salt in a large bowl and stir to combine.
Step 2In another large bowl, combine the eggs, milk, buttermilk, oil, sour cream, butter, bell pepper and jalapeno and stir to combine. Add the wet ingredients to the dry and mix thoroughly.
Step 3Pour the batter into the pan and bake until firm in the center and golden on top, 30 to 35 minutes. Let cool 15 to 20 minutes before serving.