A custard cream is a type of biscuit popular in the British Isles.
Its structure is that of a sandwich, with a creamy, custard-flavored center between two flat biscuit layers.
Traditionally, the filling was buttercream (which is still used in home-made recipes).
Nowadays cheaper fats have replaced butter in mass-produced biscuits.
The filling tastes of vanilla and as such is more akin to the taste of custard made with custard powder than egg custard.
It is believed that the custard cream biscuit originated in 1908.
They usually have an elaborate baroque design stamped onto them, originating in the Victorian era and representing ferns. (source)
So can hamsters eat custard creams?
Unfortunately they cant.
They are far too sweet for them.
If they were to nibble them they should be fine but they shouldn’t really be fed purposely to them.