This is essentially a winter dish, made with root vegetables, but in fact there's no reason why it shouldn't work equally well with some of the tender early summer vegetables such as young carrots, courgettes and French beans.
175g butter beans
4 sticks celery
125g grated cheese
freshly ground black pepper
Soak, rinse and cook the butter beans as usual, then drain them, reserving their liquid. Make the liquid up to 400ml with the milk.
Peel and dice the carrots and swede; clean and slice the leeks and celery; peel and slice the onions. Cook all the vegetables together in boiling salted water until they're just tender, then drain them.
Melt the butter in a good-sized saucepan and stir in the flour; when it 'froths', draw the saucepan off the heat and stir in the milk, then return the saucepan to the heat and stir until the sauce thickens. Let the sauce simmer gently for about ten minutes, to cook the flour, then stir in half the cheese, the butter beans and cooked vegetables. Season with sea salt and freshly ground black pepper. Turn the mixture into a shallow heatproof casserole, sprinkle with the crumbs and remaining cheese and make hot and brown under the grill.
When I made this I may have forgotten to soak my butter beans and resorted to chick peas instead and it was really good. Well I thought so and Rachael cleaned her plate so....