In a large pot of boiling water, blanch the broccoli for about 2-3 minutes. Drain and set aside.
In a large bowl, combine the shredded chicken, blanched broccoli, cream of chicken soup, sour cream (if using), garlic powder, onion powder, and half of the shredded cheddar cheese. Stir until evenly mixed.
Transfer the mixture to a greased 9x13-inch baking dish. Sprinkle the remaining cheddar cheese on top. Optionally, add a layer of breadcrumbs on top for some crunch.
Bake uncovered in the preheated oven for 25-30 minutes, or until the top is golden brown and bubbly.
Let the casserole cool for a few minutes before serving.
Notes
For a lighter version, you can use low-fat sour cream and cheese.
For added flavor, try adding some herbs such as thyme or parsley.
Substitute the cream of chicken soup with a homemade creamy sauce (using milk and flour) for a healthier alternative.
Feel free to use leftover chicken or rotisserie chicken for convenience.