In saucepan put water, cocoa, and margarine. Boil, then remove from heat. Add cinnamon, soda, sugar and vanilla. In a separate bowl, beat milk, eggs and vinegar. Add this to chocolate mixture, then add flour. Pour into greased cookie sheet or sheetcake pan. Bake at 350~ for 30 minutes. Frosting. In saucepan put margarine, cocoa, milk, vanilla and confectioners' sugar to warm only. Prick hot cake all over with fork and pour warm icing all over. I make this often...it's easy and GOOD! YUM! Kay. ----