This comforting yet luxurious gratin can be served as a main course or side-dish. Celeriac is often served raw in a mustardy sauce as celeriac rémoulade, and this dish uses the same flavour ...

A hearty gratin that's a real winter wamer. Preheat the oven to 200C/180C Fan/Gas 6. Butter a wide 3-litre/5¼-pint ovenproof dish. Put the potatoes into a large saucepan, cover with water.