Heat the oven to 180ºC fan. Grease and base line a 20x20cm rectangle brownies tin.

Mix together the banana puree, lemon juice, oil and water and mix until light and smooth. Add the sugar gradually until well blended.

Stir in the flour, baking powder and cocoa and fold in gently until incorporated. Stir in the chocolate chips and give a final mix, stirring thoroughly the mixture.

Transfer the mixture to the prepared tin and spread evenly. Bake for around 30 minutes or until a skewer comes out clean when inserted in the center. Remove from the oven and leave to cool. Remove from the tin and cut in squares.