This is a great recipe to make with kids as a treat, as it’s very simple and good fun putting the top circle over the chocolate and squashing the edges gently together to stop the chocolate escaping when it cooks.
This is quite a dry mixture, but don’t worry, they are meant to look a bit cracked and rustic, so you can’t really go wrong! If you eat these when they have just been cooked the chocolate is quite runny, and if you eat them cold they are nice and gooey. You’ll need two cutters, one about 4cm and the other about 5cm.
Grease a large baking sheet. Cream the butter and sugar together until pale. Beat in the egg yolks, then add the flour and cocoa powder to make a dough. Turn out and knead, then pop it into the fridge for a while. Preheat the oven to 190ºC/375ºF/gas 5.
On a lightly floured surface, roll about a third of the dough out thinly, then cut out about 30 circles with the smaller cutter (you can do fewer if you want the biscuits bigger). Spread them out on the baking sheet and put a square of chocolate in the middle of each one – make sure you use all the chocolate however many you do. Then roll the rest of the dough out (I always add the leftovers from the first lot of cutting to it and knead it a bit). Cut out the same number of circles with the larger cutter and pop them on top of the chocolate, pressing gently all the way round to seal the edge and keep all the chocolate in.
Cook in the preheated oven for 10 minutes, and eat them hot or cold.