These biscuits are a dieters nightmare, basically pure butter and sugar, but they are so, so good. You have been warned!
I only call them evil, because I am helpless against them. Truly, if I could only ever eat one biscuit again...
They are the Shortbread Biscuits (Fancy) from the Country Women's Association cookbook (p. 247). Basically the recipe calls for equal amounts plain butter and flour, and then a third as much of icing sugar and (now this is what makes it special) custard powder! Four ingredients and that's it.
Then just cream together the butter and sugar, and add the sifted flour and custard powder. Form into small balls and flatten with a fork. Bake to a pale brown in a moderate oven. You can then sandwhich two biscuits together with "butter icing flavoured with vanilla". I could not find butter icing amongst the recipes in the CWA cookbook, but rang DH's family aunty who makes these as her speciality, and really she just uses icing sugar with water, maybe with a little softened butter. I just had to add the water slowly to get the right consistancy, and I forgot the vanilla. But it didn't hurt these little babies one little bit.