You can serve this with meat or fish and even as a vegetarian main course.
1 head of celery, root removed and stems and leaves washed
300ml hot milk
250ml double cream
Salt and freshly ground black pepper
150g mature cheddar, grated
60g fresh white breadcrumbs
Preheat the oven to 200C/gas mark 6. Remove the leaves from the celery and then cut the stems into approximately ½cm-thick slices.
Bring a pan of lightly salted water to the boil and blanch the celery for 3 minutes, then drain and mix with the leaves.
Meanwhile, melt the butter in a heavy-based saucepan, stir in the flour then gradually whisk in the hot milk. Bring to the boil, season and simmer for 5 minutes then add the double cream and simmer for another 3-4 minutes. Remove from the heat, stir in 120g of the grated cheese, plus the celery and leaves and transfer to an oven-proof serving dish.
Bake for 20 minutes, then mix the remaining cheese with the breadcrumbs, scatter over the top of the gratin and continue cooking for another 15–20 minutes, until browned.