Preheat your oven to 375°F (190°C) and grease a baking dish with butter or cooking spray.
In a saucepan, melt butter over medium heat. Add flour and stir for 1 minute until smooth.
Gradually whisk in milk and chicken broth, cooking for 2-3 minutes until slightly thickened.
Stir in 1 1/2 cups cheddar cheese, mozzarella cheese, and salt, mixing until smooth and creamy.
In a large bowl, combine cooked chicken, rice, peas, onions, garlic powder, black pepper, salt, Italian seasoning, and smoked paprika.
Pour the cheesy sauce over the mixture and stir until well combined.
Transfer the mixture to the prepared baking dish, spreading it evenly.
Sprinkle the top with the remaining cheddar cheese and crushed crackers or breadcrumbs (if using).
Bake uncovered for 20-25 minutes, or until the cheese is golden and bubbly.
Remove from the oven and let it cool for 5 minutes before serving.
Garnish with chopped parsley and serve warm.