What is a shortcake, you might ask? I would reply:
1. Traditionally from Scotland, but much loved by Americans (strawberry shortcake!)...
2. Something between a shortbread and a cake. By this I mean it is has the crumbly qualities of a shortbread, but the lightness of a cake. An easy way of understanding it is a shortcrust pastry with self-raising flour plus eggs.
3. Easier than either a cake or shortcrust pastry to make and will get you lots of compliments, if you're fishing.
4. Experiment with the fruit filling: replace apples with stewed quinces, or pears cooked in red wine...