Preheat the oven to 400°F.
Bring a large pot of water to a boil. Add the broccoli and cook for 2-3 minutes or until tender-crisp. Drain well and set aside.
In a medium bowl, combine 1 cup cheddar cheese, condensed soup, sour cream, milk, garlic powder, onion powder, dry mustard, pepper, and seasoned salt.
Stir in drained broccoli and chicken. Transfer the mixture to a 9x13 casserole dish. Top with remaining cheese.
In a small bowl, mix the butter and breadcrumbs. Sprinkle the topping over the chicken mixture.
Bake for 18-20 minutes, or until the breadcrumbs are lightly browned and the mixture is bubbly and hot.
Serve over rice, noodles, or mashed potatoes, as desired.
