Preheat oven to 180C.

Place half chocolate and butter in a small saucepan over low heat and stir until melted and smooth. Allow to cool slightly.

Place sugar, eggs, flour in a bowl add the chocolate and mix to combine, stir through the remaining chocolate pieces. Pour the mixture into a lightly greased 20cm x 30cm tin lined with baking paper. Bake for 35-40 minutes, cool in the tin. Cut into squares. Effie xx