step 1
Preheat oven to 180C/fan 160C/gasmark 6.
step 2
Melt the chocolate and butter together over hot water (can be melted in the microwave if you're in a hurry).
step 3
Beat together the eggs, sugar and vanilla extract/paste, add to the melted chocolate and butter, mix.
step 4
Sift together the flour, cocoa and baking powder, then fold into the rest of the mix.
step 5
Add the chopped white chocolate pieces and pour into a lined and greased baking tray.
step 6
Cook for 22 minutes (the knife should come out clean when cooked), allow to cool, cut into 12 and serve.