Adopted from the Guardian’s sources of fantastic food ideas.
We tested two different products so far. First edition of these cookies was sensibly thick, as, say, thinner edition of butter cookies might be. The second was as thin as we could make it. We found them to be different enough to warrant continued experiments. My finding so far is that the thicker ones make an excellent general cookie, while the thin edition will likely complement other offerings (like e.g ice cream or mouse), rounding the taste nicely.
Also. we made individual biscuits right away and baked them on two separate sheets (real estate limitations!). In my next attempt, I will follow the initial instructions (a single sheet of dough, cut into small pieces at the very end of the production cycle..) and note the difference.
Here is my experiment with the single sheet cut post factum. It is clear it was not rolled thin enough, had to stay in the oven longer, still not suitable for the breaking-random-shape concept, not at all crunchy, but still tasty solid cookie. I may try again, but for the high confidence events will follow the single round architecture. 
As the recipe requires a modest effort and the dough keeps very well in a fridge for several days, worry not in the least about having any extra – and it freezes well.
Do the ready make cookies keep well? Will let you know..
Recommended quantities (20 thicker pieces, 30 thin ones, each piece about 5cm (2 in) in diameter.
- 115g unsalted butter,
- 100g dark muscovado sugar; I also successfully used the basic brown sugar instead,
- 1 egg, beaten gently with a fork,
- ½ vanilla pod, split, scraped, finely chopped,
- 1 tsp ground ginger,
- ¼ Tsp ground allspice,
- 150g 00-grade plain flour,
- ½ Tsp baking powder,
- A pinch of salt.
- Line a baking sheet with a piece of baking paper.
- Cream the butter and sugar in a bowl until peaked.
- Slowly add the beaten egg to the butter and sugar.
- Add the vanilla seeds, ginger, and allspice.
- Sift the flour and baking powder, then add to the bowl with the salt.
- Deftly mix the mixture into a dough.
- Halve the dough and shape each piece into a roll. Wrap these well in baking paper and twist the ends as for a cracker. Refrigerate for at least an hour or two, if not overnight.
- When ready, cut into thin slices and arrange these on the lined baking sheet.
- Lay a similar-sized sheet of baking paper over the slices and carefully rub them smooth into a thin sheet of dough, say 2mm or so thick. The edges do not have to be neat.
- Put in the fridge to set for an hour or so.
- Set the oven at 160C/325F.
- Remove the sheet from the fridge. Carefully peel away the top layer of baking paper.
- Bake in the hot oven for 12 minutes Remove.
- While the biscuit is still hot, carefully cut slices across the dough with a sharp knife to make triangles and fans.
- Leave to cool.
- Then serve with (or without) the ice cream.