a) Preheat oven to 190C or 375F, butter pan and line it with paper
b) Shift flour with cocoa powder. Put aside.
c) Melt chocolate with butter in water bath
d) Remove from heat and stir in eggs, vanilla and sugar.
e) Beat in the flour into the mixture.
f) Gently fold in chocolate and walnut.
g) Bake for about 35 minutes.
h) Let to cool and cut into squares. Enjoy!