Sieve the flour in a large bowl. Grate in the butter, coating with flour as you grate. Rub in the butter until fine crumbs are achieved.
Stir in the sugar and chocolate. Make a well in the centre and add the egg and milk. Fold together gently, but don't over mix. Add more milk if the mix is very dry, but be careful not to add too much - you want a stiff mix that will hold its shape on the baking tray.
Using a dessertspoon, place spoonfuls of the mixture onto a greased baking tray.
Bake in a preheated 200 C / Gas 6 oven for 15 to 20 minutes, then cool on a wire rack.