Step 1 of 5

Blanch the beans and stop them cold

Heat the oven to 400°F. Boil the green beans in well-salted water until just tender with a squeak left in them, then drain and plunge them straight into iced water. Drain again and dry them well.

— The iced water is not optional. It stops them cooking instantly and keeps them green rather than the drab khaki of a casserole left to overcook.