Cut the carrots, parsnips, sweet potato, and butternut squash in 1 to 1 1/4-inch cubes. All the vegetables will shrink while baking, so don't cut them too small.
Place all the cut vegetables in a single layer on 2 baking sheets. Drizzle them with olive oil, garlic powder salt, and pepper. Toss well. Bake for 25 to 35 minutes, until all the vegetables are tender, turning once with a metal spatula.
Sprinkle with parsley, season to taste, and serve hot.