Emma's Broccoli Rice Casserole

1 20 oz. pkg. frozen broccoli, thawed
4c. cooked rice (2 cups water - 1 cup rice)
1 can cream of mushroom soup
1 can cream of chicken soup
Half cup dried onion ( I use regular onion), Sautéed in
2 Tbsp. butter or oleo
1 cup milk or more
1 cup grated cheddar cheese or large jar Cheez Whiz
salt and pepper to taste