Preheat your oven to 375°F. Grease a 10-inch cast iron skillet or a 9x13 casserole dish. I like to use a little bacon grease for this — just dip a paper towel in the grease and rub it all over the bottom and up the sides. Butter, shortening, or cooking spray work fine too.
Cook your bacon ahead of time. I usually bake mine in the oven on a sheet pan, which keeps things easy and less messy. You want it mostly crispy but not overdone, since it's going back in the oven inside the casserole. Set the bacon aside on a paper towel–lined plate to drain, then crumble it into small pieces. Reserve some crumbles for the topping.
Combine everything in a large bowl. Start with the Jiffy Corn Muffin Mix and add the cream style corn, diced green chilies (drain them first if they seem extra juicy), melted butter, eggs, sharp cheddar cheese, sour cream, green onion, bacon, salt, and pepper. Stir it all together until it's just combined — don't overmix.
Pour the mixture into your greased skillet or dish. Spread it out evenly with a spatula.
Bake for 20 minutes. Then pull it out and sprinkle reserved bacon, extra shredded cheese, and a few more green onions across the top.
Return to the oven and bake for 10–12 more minutes, until the casserole is set in the center and the cheese on top is melted and just starting to get golden. My oven runs a little quick, so yours might need a few extra minutes — it could take up to 40 minutes total depending on your oven. Just keep an eye on it.
Let it cool for a few minutes before serving. It's going to smell incredible — that's the hard part. But give it just a few minutes so it holds together when you scoop it out.