Roast Parsnip and Chestnut Crumble on Bubble and Squeak

This dish makes a great alternative vegetarian Christmas lunch that includes all those familiar traditional flavours. It can be eaten on its own, or you can use this recipe as your total accompaniment to roast turkey. It can also be made any time of the year (perhaps leaving out the chestnuts!).

You can buy cooked chestnuts in tins or frozen. If you are using fresh chestnuts in shell, you will need about 223 g (8 oz). Pre-heat the grill. Pierce the chestnuts once with a knife, then