Preheat oven to 170c
Melt the dark chocolate and butter.
Using an electric whisk, whisk the sugar and eggs until pale and fluffy and tripled in volume.
Mix together the flour, baking powder, cocoa powder and chopped chocolates
Combine the melted chocolate and flour mixes together until well mixed
Fold in the egg mixture
Pour into a greased baking tray and cook for 20 mins