Preheat the oven to 180 ° C. Line a 40 x 40 cm baking pan or baking dish with parchment paper.
Melt the chocolate and butter together. Put the flour with the sugar, baking powder, salt and the melted chocolate in a bowl. Stir in eggs and nuts and pour the batter into the baking pan. Bake for about 25-30 minutes. Let cool down briefly and then cut into cubes.
The brownies can be packed in an airtight can for about a week. For some time now I have preferred to bake the brownies in a muffin tray, the amount of dough is exactly 14 pieces.