Preheat your oven to 375°F (190°C). Lightly grease a baking dish to prevent sticking.
Bring a pot of water to a boil and blanch the broccoli florets for 2 minutes. Drain and set aside.
In a mixing bowl, combine cream of chicken soup, sour cream, mayonnaise, garlic powder, onion powder, salt, and black pepper. Stir well until smooth.
Spread the cooked chicken in the greased baking dish. Evenly distribute the blanched broccoli over the chicken. Pour the prepared sauce over the top, ensuring everything is coated.
Sprinkle shredded cheddar cheese over the casserole. In a small bowl, mix breadcrumbs with melted butter and evenly spread over the top for a crispy finish.
Place the dish in the oven and bake for 25–30 minutes, or until the casserole is bubbling and the top is golden brown.
Remove from the oven and let it sit for 5 minutes before serving. Enjoy this creamy, flavorful dish with rice, pasta, or on its own.