Preheat oven to 350 degrees. Chop the onion and grate the cheddar cheese.
In a large skillet, brown the ground beef. Add the chopped onion and green chile's and cook until tender. Season with chili powder, kosher salt, and freshly ground black pepper.
In a large mixing bowl, combine the cornmeal, all-purpose flour, kosher salt, baking soda, whole milk, creamed corn, large eggs, and vegetable oil.
Assemble the Casserole
To assemble the dish, pour half of the cornmeal batter into a greased 9 x 13" baking pan.
Cover with the meat mixture. Sprinkle with cheese.
Pour remaining cornmeal batter over the meat and cheese. Bake in preheated oven for 35-40 minutes until golden brown.
Serve with shredded lettuce, sour cream, and salsa. Serves 6-8.