1. Preheat the oven to 425 degrees F.
2. Cut the carrots, parsnips, sweet potato, and butternut squash into 1 inch cubes. All the vegetables will shrink while baking, so don't cut them too small.
3. Place all the cut vegetables in a single layer on 2 baking sheets. Drizzle them with olive oil, butter, salt, pepper and thyme. Toss well.
4. Bake for 25 to 35 minutes until all the vegetables are tender, turning once with a metal spatula.
5. Sprinkle with parsley; season to taste; and serve hot.