Frosted Cake

FOR CAKE
21/4 C cake flour
21/4 tsp baking powder
4 Tbsp margarine
11/4 C sugar
4 eggs
1 tsp vanilla
1 Tbsp orange peel
3/4C skim milk

FOR ICING
3 oz lowfat cream cheese
2 Tbsp skim milk
6 Tbsp cocoa
2 C confectioners’ sugar, sifted
1/2 tsp vanilla extract