Preheat the oven to 390°F (200°C). Heat the oil in an oven safe skillet (about 9 inches (23cm) wide). Add the peppers, onion and corn and cook over medium high heat for 5 minutes.
Take off the heat and stir in the shredded chicken, salsa and barbecue sauce. Flatten and smooth the surface with the back of a spoon.
In a medium bowl stir together the cornbread mix, sour cream, egg and melted butter. Gently spread over the casserole filling, careful not to mix them together. Leave a small edge to allow steam to escape.
Bake for 15-20 minute in the middle of the preheated oven.
Scatter the cheese over the top and finish baking for 2-3 minutes or until the cheese is all bubbly and melted.