Step 1 Preheat oven to 175°C and lightly spray or oil a 20x20cm baking dish.

Step 2 Place purée in a medium-sized bowl. Sift in cocoa, flour and baking soda. Add sugar and salt. Mix until just combined (do not over-mix as this will toughen the brownies). Gently fold in chocolate chips and walnuts. Transfer to prepared baking dish. Bake for about 25-30 minutes or until the centre feels set and fudgy when a skewer is inserted.

Step 3 Cool in pan for 5-10 minutes before turning out. Cool completely before slicing into squares. Dust with sifted icing sugar before serving, if desired.