Preheat oven to 375°F (190°C). Lightly spray a 9x13 casserole dish with cooking spray.
Prep broccoli:
Steam or blanch broccoli florets for 2–3 minutes until just tender. Drain and set aside.
Mix the base:
In a large bowl, combine the cream of chicken soup, Greek yogurt, garlic powder, onion powder, salt, pepper, and 1/4 cup cheddar cheese.
Add chicken and broccoli:
Fold in the cooked chicken, broccoli, and cooked rice (if using). Stir until well coated.
Assemble the casserole:
Pour the mixture into the prepared dish. Sprinkle with remaining cheddar and Parmesan cheese. Add breadcrumb topping if using.
Bake:
Bake uncovered for 25–30 minutes, or until the cheese is melted and the top is lightly golden.
Serve:
Let cool for a few minutes before serving.