Preheat oven to 350°F. Mist a 9-by-13-inch baking dish with cooking spray. In a large bowl, toss carrots, cranberries, apples, cider, brown sugar and salt and mix well. Transfer mixture to baking dish. Dot with butter.
Tightly cover baking dish with foil and bake, stirring once or twice, until cranberries are soft and carrots are cooked through, 40 to 50 minutes. Serve warm.