Season chicken with salt and pepper and sear in a hot skillet with a bit of olive oil until golden, about 4–5 minutes per side. Transfer to a pot, cover with water or broth, and simmer 12–15 minutes until cooked through. Let rest, then shred. (Shortcut: use rotisserie chicken.)

In a large bowl, beat together cream cheese, sour cream, mayonnaise, garlic, smoked paprika, chili powder, cumin, lime zest, and half the lime juice until smooth. Stir in the corn, jalapeño (if using), half the cotija, and the shredded chicken. Taste and season with salt and pepper.

Spread the mixture into a greased 9x13-inch baking dish. Top evenly with Monterey Jack and cheddar. Sprinkle crushed tortilla chips or panko over the cheese if you want crunch.

Bake at 375°F (190°C) for 20–25 minutes until cheese is melted and edges bubble. For a golden top, broil 1–2 minutes, watching carefully.

Let casserole rest 5 minutes. Sprinkle with remaining cotija, cilantro, green onions, and a squeeze of lime juice. Serve warm with tortillas, rice, or a crisp salad.