3 tbsp olive oil
4 garlic cloves, peeled and chopped
2 fresh red chillies, finely chopped (or 1 tsp dried chilli flakes)
6 anchovy fillets, finely chopped
1 large sprig rosemary, leaves finely chopped
salt and black pepper
500ml single cream (or double, if you're greedy)
preheat the oven to 190C/375F/ gas mark 5 and use a little oil lightly to grease a fairly large gratin dish. Peel the celeriac and slice it very thinly (2p-piece thickness is good). Roughly combine the garlic, chilli, anchovy and rosemary.
put a layer of celeriac in the base of the dish, sprinkle with the aromatic mixture and season. Repeat the layers until you've used up everything. Pour the cream on top: just enough so it's visible around the edges of the dish, not so much as to cover the celeriac. Drizzle with oil and bake for 40-50 minutes, until the celeriac's tender and the top browned and crisp. For extra crispness, finish under the grill.