Preheat oven to 180°C.
Line a rectangular 8inch square baking tray with greased baking paper.
In a bowl add walnuts, brownie mix, melted butter, milk and whisk well until the batter is smooth.
Bake for 25 minutes or until a toothpick inserted in the centre comes out clean. Leave to cool.
Cut the brownie cake into 12 pieces & serve as desired.