Brownie

1. 1 Mix the cocoa powder, butter, and water in a pot. Cook over medium heat, stirring constantly, until the butter has melted. Remove from the heat and let cool slightly.
2. 2 Sift together the flour, sugar, and baking soda. Add the chocolate mixture, stirring constantly with a wooden spoon.
3. 3 Add the eggs and yogurt. Mix well. Pour into a greased baking pan (28.5 x 21 cm).
4. 4 Bake in a preheated moderate oven (170°C) for 35 to 40 minutes.
5. 5 Cut into small squares and serve.

Icing

1. 6 For the icing, place the chopped chocolate with the butter in a water bath.
2. 7 Mix until it forms a cream, add the nuts, and spread over the baked, cooled dough.