Sift together flour, cocoa, and baking powder. Mix in rolled oats and brown sugar.

Rub in butter and add cold water as needed to fully incorporate the ingredients.

Roll out to 2-2.5cm thick (I’m pretty sure Nan’s recipe says 8 inches thick, which we all know would be like basically a tower, so that must be a mistake, or I just cannot read her handwriting! She also doesn’t say to cut this into biscuits, but yeah, I would get out your favourite biscuit cutter and cut these into shapes before popping onto a lined oven tray).

Bake in the centre of the oven at 160°C for 10 minutes.