Preheat your oven to 375°F (190°C). Grease a 9x13-inch baking dish with non-stick spray.
Arrange the chicken breasts in a single line down the center of the baking dish. Place the quartered potatoes on one side of the chicken and the green beans on the other.
Sprinkle the entire packet of Italian dressing mix evenly over the chicken, potatoes, and green beans. Drizzle the melted butter over the top.
Cover the dish with aluminum foil and bake for 40 minutes. Remove the foil and bake for an additional 20 minutes, or until the chicken is cooked through (internal temperature of 165°F) and the potatoes are tender.
Let the casserole cool for a few minutes before serving. Plate up the chicken with a generous helping of potatoes and green beans, and enjoy!
