Preheat the oven to 190ºC / 375ºF / Gas mark 5.
Peel the swede, potatoes and carrots and chop into bite-sized pieces, chopping the swede and carrots into smaller chunks than the potatoes as they will take longer to cook. Put in a roasting tin with the peppers, chillies and thyme and drizzle with the olive oil, turning the vegetables over with a large spoon until they are coated.
Season and roast for 40 minutes, turning the vegetables once or twice. Pour the pasta sauce around the vegetables and return to the oven for 15-20 minutes or until everything is tender. Stir well before serving.