Preheat oven to 180ºC . Spray and flour a 9x13 inch pan. Melt margarine and chocolate together in microwave. Cream sugar and eggs. Combine margarine-chocolate with sugar-eggs. Add vanilla and flour; add optional nuts and chips/bits of chocolate (up to 1 cup each). Bake for 30 to 40 minutes. Should be quite wet after baking for really moist brownies. Cool completely befor cutting. Cut ahead. Freeze. Place on waxed paper "floors" when packing. Serve frozen or slightly thawed. Makes 24 or how ever many bite-sized brownies.