I have a strong suspicion that I already wrote this recipe up somewhere, but I can't find it, so here it is again. The proportions got gradually modified over the years and the result is now much more chocolatey, so it not completely the same anyway. The "original recipe" was found in one of the blogs under livejournal umbrella; there it said that it was copied (also modified, I think) from a book.
Anyway, here it is as I make them now.
225 g chocolate, broken into pieces. Тhe type of chocolate depends on your preference. Didn't try the white one though, probably won't look as nice.
60 g unsalted butter
1 teaspoon salt
90 g sugar
200 g plain white flour
1 teaspoon baking powder
Icing sugar to form a white crust; optional (see below)
Cover and put into the fridge for at least a couple of hours to harden and make it easier to manipulate. It can stand in the fridge overnight. I didn't experiment with longer periods.
Line a tray with parchment.
Pour some icing sugar on a small plate.
Start your oven to 170 °C (approx, you'll need to experiment).
Take walnut-sized bits of dough and roll them into balls between your palms. Ice-cream scoop can make the job easier, but tablespoon will do.
Roll the balls in icing sugar till covered (optional) and put them onto the tray, leaving some space between them.
Bake for about 12 minutes. They will flatten and crack somewhat, see the very first pic.
Now, about the "optional" steps. Icing sugar makes them more festive-looking, but if you don't have it at hand, or don't like additional sweetness, or think (correctly) that it is making eating process messier, you can leave it off.
The result will look more like a "normal" chocolate cookie, but it still will be nice to eat :)
Of course you can use some other type of coating, to your liking - crushed nuts, coconut flakes, chili and salt for the brave souls... I am sure you can think of something.
Enjoy the process and the result :)
Baked stuff on shutterstock - here