Preheat oven to 350 degrees. Lightly oil a 9 inch square baking pan.
In a large bowl, sift the dry ingredients until combined.
Add the wet ingredients, slowly mixing to gently combine.
Optional: fold in the walnuts!
Pour batter into baking pan.
Bake for 45-50 minutes in the middle rack of your oven, turning pan halfway through for even baking.
Let cool completely on wire rack, then chill to harden in refrigerator for 1 hour before slicing.
Dust with icing sugar if you so wish – this is done by holding a little wire sieve on top of the brownies, sprinkling icing sugar into the sieve and shaking it around, creating a light dust of powdery sugar. Fresh berries add a bright blast of colour too! Enjoy!