Preheat the oven to 400 degrees F. Spray an 8×8 Pyrex baking dish with nonstick cooking spray and set aside.
Whisk together the flour, cornmeal, sugar, baking powder, baking soda, and salt in a large bowl.
In a separate medium bowl, whisk together the buttermilk, melted butter, oil, and eggs. Pour the liquid ingredients over the dry ingredients and stir until combined. The batter will be lumpy.
Add corn kernels, green chiles, and cheddar cheese to the batter and stir until just combined.
Cool in pan before cutting into squares and serve.
Pour batter into prepared pan, and bake on center rack until the top is golden brown and a toothpick inserted into the middle comes out clean – about 30-35 minutes.