Heat oven to 350. Grease a 9x13 pan. In medium bowl, stir together margarine, sugar and vanilla. Add egg; with spoon beat well. I used a electric mixer.
Stir together flour, cocoa, baking powder and salt. Add to the liquids and beat very well. Pour in prepared pan.
Bake for 25-30 mins or until the brownies start to pull away from the side. Cool completely in the pan on a wire rack.
You can frost your brownie or use powdered sugar to top your brownie. I used left over frosting microwaved for 7 seconds and drizzled it over my brownies.