What to do with leftover egg whites

A quiet morning, a bit of a catch-up after 3 good, busy days.
A little plastic container of leftover egg whites has been sitting in the fridge for several days. To date I've not found a recipe for using up spare egg whites that really fits the bill. But this one worked well: almond biscuits from the Penguin cookery book of many years ago, by Jill Norman. I replaced the suggested icing sugar in the ingredients list with date syrup, and the biscuits seemed to survive the experiment. They're a bit more rustic than JN proposes, but that's fine by me.  We've just watched season 5 of Fargo, in which baking plays a significant part; perhaps that was at the back of my mind.  Highly recommended, all 5 Fargo seasons.
Josh, Ruth and the boys are due to be with us for tea, after a weekend away visiting Josh's mum in N Oxfordshire.