Prepare the pan: Grease with a small amount of cooking oil, or use nonstick cooking spray, a 10-inch round pan (at least 2½ inches deep). Powder pan with flour. Tap out excess flour.
In a mixing bowl, sift together the cake flour and baking powder.
In a separate bowl, beat together the margarine and sugar until soft and creamy.
Beat in eggs, vanilla, and orange peel.
Gradually add the flour mixture alternating with the milk, beginning and ending with flour.
Pour the mixture into the pan. Bake for 40 to 45 minutes or until a toothpick inserted in the center of the cake comes out clean. Let cake cool for 5 to 10 minutes before removing from the pan. Let cool completely before icing.
To prepare icing: Cream together cream cheese and milk until smooth. Add cocoa powder. Blend well.
Slowly add confectionersâ€™ sugar and mix until icing is smooth. Mix in vanilla.