1. Preheat the over to 325ºF.
2. Grease with small amount of cooking oil or use nonstick cooking oil spray on a 10-inch round pan (at least 2½ inches high).  Powder pan with flour.  Tap out excess flour.
3. Sift together flour and baking powder.
4. In a separate bowl, beat together margarine and sugar until soft and creamy.
5. Beat in eggs, vanilla, and orange peel.
6. Gradually add the flour mixture alternating with the milk, beginning and ending with flour.
7. Pour the mixture into the pan.  Bake for 40 to 45 minutes or until done.  Let cake cool for 5 to 10 minutes before removing from the pan.  Let cool completely before icing.

Icing:

1. Cream together cream cheese and milk until smooth.  Add cocoa.  Blend well.
2. Slowly add sugar until icing is smooth.  Mix in vanilla.
3. Smooth icing over top and sides of cooled cake.