Fairy cakes are small versions of cupcakes made in the UK.
They are made exactly from the same batters that you would use for cakes; plain ones, for instance, are usually plain white sponge.
Fairy cakes are made in muffin tins with smaller cups, and smaller lining papers than cupcakes. Ideally, the tops should come out flat. A challenge is that the tops often end up domed rather than flat. You can compensate by trowelling on enough thick icing to level them off.
They are iced, often with coloured icing, and then often sprinkled with “hundreds and thousands”, or decorated with candied peel or flowers made from icing, or silver balls.
They used to always be served at girls’ birthday parties, and at those for many of their brothers as well.
There is a misunderstanding in North America that they are decorated to “look like fairies.” In fact, they are called Fairy Cakes because they’re thought to be small enough for the fairies to eat, and pretty enough to attract them. The ones that North Americans are thinking of, with “wings” are a closely-related version, Butterfly Cakes.
You can also buy bags of undecorated Fairy Cakes at supermarkets to take home and decorate yourself.