1Preheat oven to moderate, 180 C. Lightly grease and line a 20 cm square cake pan with baking paper.
2In a bowl, using an electric mixer, beat butter, sugar and vanilla together until light and creamy. Beat in egg. Fold in combined sifted flours.
3Press mixture evenly and firmly into pan.
4TOPING In a large bowl, combine all ingredients. Spread over base.
5Bake 40 to 45 mins. Cool in pan.
6Drizzle with chocolate. Chill until chocolate is set before cutting into squares. Store in an airtight container.
Tip: Use floured fingertips when pressing base mixture into pan to prevent it from sticking.
Photo: Rob Shaw:bauersyndication.com.au