Melt chocolate and butter using a double boiler method (with a metallic bowl on top of boiling water, making sure just the steam contacts the bowl so it warms evenly).
Beat the eggs with a hand mixer until creamy and soft.
Add the chocolate to the eggs and start incorporating sugar, flour, and baking powder, trying not to beat too much.
Freeze the batter for 30-45 minutes.
Preheat the oven to 325º.
Line a tray with baking paper.
Place powdered sugar on a deep plate.
Make balls with the batter and cover them with powdered sugar, arrange them in the tray.
Bake for around 10 minutes.
Let them cool before removing them from the baking paper.