Preheat the oven to 180ºC, fan 160º, gas 4. Bring a large saucepan of water to the boil and cook the parsnips until tender. In a medium saucepan, heat the oil, add the onion and garlic and cook until softened.
Meanwhile, whizz the walnuts and cashews and stir though the breadcrumbs. Add the onions, garlic, pine nuts, rosemary and half of the cranberries to the mix. Then beat in the egg.
When the parsnips are tender, drain and mash with the butter. Alternatively, blend in a food processor.
Mix the parsnip mash with the rest of the mix, then fill a 1.5-litre loaf tin with the mixture. Bake for 50-55 minutes until set.
Turn out on to a plate and heat up the cranberry sauce with the rest of the fresh cranberries. Spoon it over the top of the nut roast, then garnish with the extra fresh cranberries and rosemary sprigs to serve.