Preheat & prep: Heat oven to 375°F (190°C). Grease a 9×13-inch baking dish.
Mix filling: In a large bowl combine chicken, sour cream, broth, diced tomatoes, peppers, onion, 1 cup cheese, fajita seasoning, and cilantro; stir to coat evenly.
Assemble: Spread mixture into the baking dish. Top with remaining 1/2 cup cheese.
Crumb topping: Toss Panko with a drizzle of olive oil or melted butter until lightly moistened; sprinkle over the casserole.
Bake: Cover with foil and bake 25–30 minutes until hot and bubbling. Uncover and bake 8–10 minutes more until the crumbs are golden.
Finish: Rest 5 minutes. Garnish with cilantro, avocado, and lime wedges. Serve warm.
Tips, Swaps & Make-Ahead
Rotisserie shortcut: A store-bought rotisserie chicken makes this extra fast.
Spice level: Add minced jalapeño or a dash of chipotle powder for heat; use mild seasoning for kids.
Low-carb option: Skip the Panko and finish with cheese only, or swap crushed pork rinds for crunch.
Veggie boost: Add black beans or corn (well drained) to the mix.
Storage: Refrigerate 3–4 days; reheat covered at 325°F until hot. Freeze up to 2 months (thaw overnight, then bake until warmed through).
