Preheat your oven to 350°F (175°C). Lightly grease a 9x13-inch baking dish.
In a large bowl, whisk together cream cheese, sour cream, mayonnaise, and chicken broth until smooth.
If the cream cheese is stubborn, microwave it for 15–20 seconds to soften.
Stir in ranch seasoning, garlic powder, onion powder, smoked paprika, salt, and pepper. Taste and adjust the seasoning as needed.
Fold in the shredded chicken, mozzarella, cheddar, and half of the Parmesan. Mix until everything is evenly coated.
Spread the mixture into the prepared baking dish, smoothing the top with a spatula.
In a small bowl, combine pork panko with the remaining Parmesan and melted butter.
Sprinkle this evenly over the casserole.
Bake for 25–30 minutes, until the edges are bubbling and the topping is golden.
Let the casserole rest for 5–10 minutes. Garnish with parsley, slice into portions, and serve warm.