Place the butternut, parsnips and onion in an oven roasting pan.
Drizzle the butter over and roast for 30 - 35 minutes or until tender.
Meanwhile, prepare the remaining ingredients.
Add to the butternut in the last 20 minutes of cooking time.
Roast until peppers are tender and skins of tomatoes start to wrinkle.
Remove from oven and serve warm as a side dish.