Stir together flour, baking powder and salt. Add milk, melted margarine and vanilla. Put batter into a greased 8 x 8 in. baking pan. Mix together brown sugar, sugar, cocoa and hot water until like a thin syrup. Pour syrup over the batter in pan, but DO NOT STIR. Bake 30 min. at 350 deg. Serve warm with whipped cream or ice cream, if desired. Top will be like cake and bottom will form a pudding. Will make approximately 8 servings. ----