Preheat oven to 350°F. Grease one 9-inch square baking pan, set aside.
Combine dry ingredients and sift them into bowl, mixing well. Combine liquids in small bowl and mix with fork or whisk. Pour over dry ingredients all at once and mix quickly. Batter will be thick; spread it thinly in pan. Scatter nuts on top of batter (optional).
Bake 20 to 25 minutes, careful not to overbake. Typically, cracks appear in top when done.
To Make a Cake:
Follow brownie recipe exactly, except increase water to 2/3 cup. Bake for 25 to 30 minutes.