Mix dry ingredients in a large bowl. Make 3 holes (1 large and 2 small). In 1 hole put 1 teaspoon vinegar, in 1 hole put 2 teaspoons vanilla, in last hole put 1 cup oil. Pour 2 cups cold water over all and mix. Pour into greased pan 14 x 10 x 2. Bake at 350 degrees for 30 to 35 minutes.
Mix 2 packages of instant chocolate pudding with the 3 cups of milk(if it seems too thick you can add another 1/2 cup of milk). When set(you can put this in the refrigerator for 30 minutes to help if you are in a hot area), spread on cooled cake in pan. Cover with Cool Whip....you can then fancy it up with sprinkles,chopped nuts,shaved chocolate,mini chocolate chips,etc...if you would like to.