
Preheat the oven to 180°C. Line a slice/brownie tin with baking paper.
In a large bowl cream the butter and sugar until smooth and fluffy. Beat in the egg and vanilla. Add all other ingredients and mix well. Scrape mixture into the prepared tin and bake for 20-30 minutes until golden brown.
Allow to cool in the tin for 10-15 minutes. Remove slice from the tin and allow to cool completely on a wire rack. Cut into squares when cool.