Bring a large pan of salted water to the boil, add the parsnips and cook for 3 minutes until just soft. Drain the parsnips thoroughly, before returning them to the pan and then tossing together with the polenta or flour, grated Parmesan and thyme.
Preheat the oven to gas 6, 200°C, fan 180°C. Heat the olive oil in a roasting tray. When bubbling, carefully add the parsnips and coat them in the oil.
Cook for 25 minutes until golden and lightly crisp.
See more Christmas recipes