Mix crushed cereal with melted margarine. Set aside. Stir together flour, baking powder, and salt. Set aside. Beat the quarter cup margarine, the sugar, and egg until well blended. Add milk alternately with flour mixture, mixing until smooth. Spread batter in greased 23 cm round cake pan. Top evenly with cranberry sauce. Sprinkle with cereal mixture. Bake at 180ºC about 50 mins. Serve warm or cooled.