Sift the flour with the baking powder and salt.
Chop the chocolate and nuts with a knife - coarser or finer, whichever you prefer.
Melt the butter and margarine, then add the vanilla and regular sugar. Whisk well until the sugar dissolves.
Beat in the eggs and whisk everything together well.
Sift in the flour mixture and mix well again.
At the very end, add the nuts and chocolate and mix.
Pour the batter into a pan lined with parchment paper and spread it out. Bake in the oven at 180C for 25-30 minutes. Let the finished cake cool - and it's ready to eat. Bon appetit!