Melt the dark chocolate and butter together using a double boiler.
Sift together the cacao powder and flour, then mix well.
Add sugar and eggs, mixing thoroughly.
Add the melted chocolate-butter mixture and form a dough.
Shape the dough into rounds and place them on a pan or baking sheet.
Bake in a preheated oven at 180°C (356°F) for 15 minutes.