The chicken filling can be made a day a head and reheated before continuing with the recipe. Slideshow: More Casserole Recipes
How to Make It
Preheat the oven to 400°F. Season the chicken with 1/2 teaspoon salt and 1/4 teaspoon pepper.
In a large cast iron skillet, heat the oil over medium high heat until hot. Brown the chicken, in batches if necessary, turning occasionally with tongs, about 6 minutes per batch. Transfer the chicken to a plate. Add the onion and garlic to the skillet and cook, stirring occasionally, until golden brown, about 6 minutes. Stir in the cumin and oregano and cook, stirring, until fragrant, about 1 minute. Stir in the chipotles in adobo, tomatoes and the reserved chicken with any accumulated juices. Simmer the until slightly thickened and the the chicken is cooked, about 10 minutes. Remove the skillet from the heat.
In a bowl, whisk together the cornmeal, flour, baking powder, baking soda, and 1/2 teaspoon salt. In a separate bowl, whisk together the egg, buttermilk and butter. Whisk the buttermilk mixture into the cornmeal mixture. Pour the batter over the chicken mixture and scatter the pickled jalapeños over top.
Transfer the skillet to the oven and bake until the corn bread is set, about 25 minutes.