Preheat oven to 400 degrees.
Place the butter in a large pan and heat over medium-high heat. When melted, add onion and bell pepper.
Cook 5-6 minutes or until onions and peppers are soft.
Drain liquid from crawfish and add to pan along with creole seasoning. Remove from heat and set aside.
In a large bowl, whisk together cornbread mix and self rising flour.
Add cheese, corn, milk, oil, and eggs. Add onion/crawfish mixture.
Stir until well combined. Transfer mixture to a greased 10 inch cast iron skillet.
Bake for 35 to 45 minutes, or until golden on top and set in the middle.