Method
Heat the oven to 170ºC regular bake and line a 20cm square tin with baking paper.
In a large microwave proof bowl, melt the butter and chocolate in 30 seconds increments until glossy and smooth. Set aside for 5 minutes to cool slightly then mix in the eggs and vanilla bean paste.
In a food processor or blender, blitz the avocado flesh until completely smooth. Add to the brownie mixture and stir until well combined.
Fold in the dry ingredients and ⅔ of the chopped chocolate, then pour into the lined tin. Top with remaining chocolate and bake for 20-23 minutes or until shiny and cracking on top but still very soft.
Cool on a wire rack then place the tin in the fridge for 2 hours before slicing into small pieces with a large sharp knife.
Brownie is best kept in an airtight container in the fridge.