Place baking sheet paper in a square shape, about 20 * 30 cm.
Chop the nuts.
Melt the butter and stir down the cocoa.
Stir together eggs and sugar in a bowl. Turn down the cocoa mixture, salt, vanilla powder, nuts and flour mixed with baking powder. Spread the batter into the mold.
Bake in the middle of the oven for 20-25 min. Let cool and cut the cake into squares. Store in a refrigerator.