Melt dark chocolate and butter together using a double boiler.
Add sugar and eggs to a bowl and whisk together.
Pour in the melted chocolate and butter mixture into the egg mixture and mix well.
Sift in flour, cocoa powder, baking powder, and salt, then mix until combined.
Scoop out spoonfuls of dough, form them into balls, and coat evenly with powdered sugar.
Bake in a preheated oven at 180°C (356°F) for 12 to 15 minutes.