Put the eggs and the sugar into a bowl and mix very well. Add the melted butter, mix well, add the chocolate powder, mix it all together very well (don't leave any chocolate powder lumps in the mixture).
Finally, add the wheat flour and mix.
Grease a baking tin with butter and chocolate powder and pour the batter, spread gently.
Bake in a preheated oven at 180°C (356°F) for 30 to 40 minutes.