Assemble all ingredients. Preheat your oven to 400°F (200°C).
In a 12-inch ovenproof deep skillet, melt the butter over medium heat.
Add the chopped onion and diced bell pepper to the skillet. Sauté for 3-4 minutes, or until the onions become translucent.
Incorporate the minced garlic and cook for an additional 1 minute until fragrant.
Lower the heat to medium. Stir in the shredded chicken, white beans, chili powder, cumin, crushed oregano, salt, black pepper, and cayenne pepper, if desired. Stir well until everything is heated through, approximately 1 minute.
Blend in the green chilis, condensed cream of chicken soup, 2/3 cup of the milk, and cream cheese. Stir continuously until the cream cheese melts and combines smoothly, about 2 minutes. Remove from heat.
In a separate medium bowl, mix the cornbread mix, the remaining 2/3 cup of milk, egg, and optional chopped jalapeño until combined.
Pour the cornbread batter evenly over the chicken chili mixture in the skillet, using a spoon to smooth out the surface.
Place the skillet in the preheated oven and bake for 25-30 minutes, or until the cornbread is golden and a toothpick inserted in the center comes out clean, with the casserole bubbling around the edges.
Serve hot, garnished with fresh cilantro and lime wedges for a burst of flavor.