Photograph: Jonathan Gregson
Preheat the oven to 180°C, fan 170°C, gas 4. In a large pan, melt the butter and cook until it turns golden brown. Add all the vegetables and stir well to coat with the butter. Season, transfer to an ovenproof dish and cover. Cook in the oven for about 45 minutes to 1 hour, or until the vegetables are tender.
Get ahead: prepare the vegetables a couple of hours ahead, ready for roasting.