Dice chicken breasts and boil in at least 2 cups of water until fully cooked. Reserve the cooking water for rice preparation.
Remove chicken from water and transfer to a sauté pan with melted butter and diced onions.
Season chicken with salt, pepper, onion powder, and garlic powder. Stir and coat chicken for 2-3 minutes.
Prepare Minute Rice according to package directions using 1 2/3 cups of the reserved chicken cooking water per 7 oz of rice.
Mix sour cream and cream of chicken soup in a bowl. Season mixture to taste.
Preheat oven to 300°F.
Layer ingredients in a casserole dish: rice on bottom, seasoned chicken next, soup mixture over chicken, and shredded cheese on top.
Cover and bake for 1 hour.
Optional: Remove cover, sprinkle with French fried onions or crushed chips, increase temperature to 350°F, and bake uncovered until topping is golden and crispy.