Preheat oven to 350*. Grease 9" square pan. (Flour pan if desired.)
If using butter: Melt butter over low heat on stove top, or at 50% power in the microwave.
Meanwhile, add sugar and vanilla to mixing bowl. Then add oil, or butter when fully melted. Stir thoroughly with wooden spoon.
Stir in the eggs.
Gradually add flour, then cocoa, baking powder, and salt. (I add separately as I go. You can blend them together first if you prefer.) Stir while periodically adding dry ingredients to ensure mix is thoroughly blended together.
Stir in nuts, or other additions, if desired.
Spread into prepared pan.
Bake at 350* for 20-25 minutes, or until brownie pulls away from edges of pan. (Oven times may vary.)
Cool in pan. Frost or garnish, if desired. Cut into squares. Makes 16 brownies.
