Butter or shortening -to grease pan Separate egg whites from yolks. Set the whites aside. Preheat oven to 350 degrees. Mix yolks with sugar. Add slowly oil, then hot water. Mix in flour and backing powder. Beat egg whites alone in another bowl until they expand about 3 to 4 times. use an electric mixer on high speed for this. Add these egg whites to the batter. Mix by hand. Add vanilla if desired. Pour half into greased round angel-cake pan. Mix the cocoa into the remaining half and pour on top of the first layer in the pan. Don't mix together. Bake for 45 minutes. Check with toothpick (toothpick will not have mixture on it if the cake is done) by poking it into the cake. Sprinkle finished cake with powdered sugar. You could also add raisins or nuts to the original batter or pour chocolate on top of the finished cake. ----