1. Preheat oven to 325F degrees.
2. Grease and flour an 8-inch square pan and set aside.
3. In a mixing bowl, combine baking powder, cocoa, salt, and flour.
4. In another mixing bowl, combine beaten egg, egg whites, sugar, vanilla, and marshmallow creme.
5. Mix dry ingredients with wet ingredients.
6. Do not overmix or brownies will be too tough.
7. Pour into prepared pan.
8. Sprinkle nuts on top, if using.
9. Bake for 18-20 minutes.
10. Ice with your favourite chocolate or vanilla icing if you wish.