Watercress & Gruyère soufflé

Soufflés are a fine thing yet often associated with complications. They are, however, easy to make but, having said that, they behave as I do in a church service: after the vicar has whispered ‘all stand’, I spring up, but after only seconds, my rigid posture more resembles a sulking teenager. Get guests to the table quickly; a little neurotic fussing is acceptable.