Sweet corn and spicy chorizo make this side dish taste like a deconstructed tamale.
Preheat the oven to 350°. Heat a large skillet over medium. Add the chorizo. Cook, stirring often and breaking up with a spoon, until browned, about 5 minutes. Using a slotted spoon, transfer to a large bowl. Add the onions, carrots, celery, and garlic to the skillet. Cook, stirring often, until the vegetables brown, about 10 minutes. Stir in the cornbread and 1/2 cup cilantro, if using; add to the bowl with the chorizo. Gradually stir in the stock to make a moist (but not soggy) stuffing.
Grease a 9-by-13-inch baking dish or large ovenproof skillet with the butter. Add the stuffing to the dish. Bake until heated through, about 20 minutes. Turn on the broiler and broil until browned on top, 2 to 3 minutes. Garnish with Cotija and additional cilantro, if using.