Preheat the oven to 425 degrees.
Cut the carrots, sweet potato, and butternut squash in 1 ½ inch cubes. (You do not want to cut them too small as they will reduce in size.) Place all the cut vegetables in a single layer on 2 baking sheets. Drizzle them with olive oil, salt, and pepper. Toss well to coat all the vegetables. Bake 25-30 minutes, until all the vegetables are tender, turning one time.