Preheat the oven to 350°F (175°C).
In a medium saucepan, melt 2 tablespoons of unsalted butter over medium heat.
Add the Chicken Rice-A-Roni pasta and seasoning mix from the box to the melted butter. Cook and stir for 2 to 3 minutes until the pasta is golden brown.
Add 2 cups of water to the saucepan and bring to a boil.
Reduce heat to low, cover, and simmer for 15 minutes, or until the rice is tender and the liquid is absorbed.
While the rice is cooking, steam the broccoli florets until tender but still crisp, about 4 to 5 minutes. Drain and set aside.
In a large mixing bowl, combine the cooked Rice-A-Roni, cooked chicken, steamed broccoli, condensed cream of chicken soup, sour cream, shredded cheddar cheese, shredded mozzarella cheese, black pepper, garlic powder, onion powder, and paprika. Mix until well combined.
Transfer the mixture to a greased 9×13 inch baking dish and spread evenly.
Sprinkle the grated Parmesan cheese evenly over the top of the casserole.
Bake uncovered in the preheated oven for 20 minutes, or until the casserole is bubbly and the cheese on top is melted and lightly golden.
Remove from the oven and let it rest for 5 minutes before serving.