Preheat oven to 375°F (190°C).

Cook rice according to package directions using the 2 cups of water.

In a large bowl, combine cooked rice, cream of chicken soup, cream of mushroom soup, shredded chicken, and chopped onion.

Melt butter in a saucepan over medium heat. Add milk and stir until heated through.

Stir in broccoli pieces and cook until tender-crisp, about 5-7 minutes.

Add the broccoli mixture to the rice mixture. Stir in shredded cheddar cheese.

Pour the casserole into a greased 9x13 inch baking dish.

Bake for 30-40 minutes, or until bubbly and heated through.