Preheat your oven to 350°F. Lightly spray a 9×13 baking dish with nonstick cooking spray and set it aside.
In a large bowl, stir together the whole kernel corn, creamed corn, melted butter, sour cream, egg, onion powder, garlic powder, black pepper, corn muffin mix, pepper jack cheese, and half of the cheddar cheese until well combined.
Pour the mixture into the prepared baking dish and spread it evenly across the bottom.
Place the dish in the oven and bake for 50 minutes, until golden brown.
Remove the casserole from the oven and sprinkle on the remaining cheddar cheese. Return it to the oven for an additional 10 minutes or until the cheese is bubbling.
Once done, let the casserole sit for 10 minutes before serving. Garnish with sliced green onions or chives if desired.