Celeriac adds a nutty complexity to this classic dauphinoise. Serve this creamy, garlicky side dish with your favourite Sunday roast or a baked ham.
- butter, for greasing
- 500ml/18fl oz double cream
- 1 tbsp Dijon mustard
- 1 tbsp finely chopped fresh rosemary
- 2 smoked garlic cloves (or regular garlic if smoked unavailable), crushed
- 400g/14oz celeriac, peeled and very thinly sliced (ideally with a mandolin)
- 400g/14oz Maris Piper potatoes, peeled and very thinly sliced (ideally with a mandolin)
- 100g/3½oz Parmesan (or a similar vegetarian hard cheese), grated
- salt and freshly ground black pepper
For the dauphinoise, grease a large baking dish with butter and preheat the oven to 200C/180C Fan/Gas 6.
Add the cream, mustard, rosemary and garlic to a saucepan. Stir well and bring to a simmer. Remove from the heat and season generously with salt and pepper. Toss the celeriac and potatoes in the cream sauce to coat then arrange layers of the sliced vegetables in the prepared dish. Pour any remaining cream sauce over the top.
Cut a piece of baking paper large enough to cover the top of the baking dish. Place on top of the dish and then place a heavy baking tray or ovenproof dish on top, to weigh down the ingredients. Bake for 1 hour, then take out of the oven and remove the paper and baking tray. Sprinkle with the Parmesan and return to the oven for a further 15 minutes to brown the top.