Cold Lemon Soufflé

This is a pretty retro dish but doesn’t deserve to be forgotten as, along with lemon curd, I think it takes its place at the top of the lemon pudding list. Making this is also a good way to hone your skills at folding in beaten egg whites. The lemons must have firm, slightly rough skins; if firm but smooth you won’t be able to grate the zest so easily.