In a large bowl, combine all the dry ingredients (cornmeal through Splenda) and mix well. Make a hole in the center and pour in the milk and vanilla. Use a wire whisk to gently mix in the liquids, using a circular motion.
In a separate bowl, whip egg whites until fluffy. Pour into mixture and mix in.
Pour mixture into muffin cups or cake tin, and bake in a hot water bath* at 350 degrees for 45 minutes.
* To prepare a water bath for baking, put your filled muffin trays or cake tin in a larger pan and add enough boiling-hot water to reach halfway up the side of the smaller pan.