In a large bowl, combine flour, cocoa powder, baking powder, baking soda, cinnamon and salt.
Make a well in the center of the ingredients and set aside.
In a medium sized bowl, applesauce, brown and white sugars, eggs and egg whites, zucchini, rum, buttermilk and oil.
Beat for 1 minute with a handheld mixer on medium/low until frothy.
(Use a small grater holes for grating the zucchini. It is not necessary to peel them, but make sure they are well-rinsed.- Drain any excess water from the grated zucchini before using. Place in colander and let drain for about 10 minutes before using. Do n) Pour applesauce mixture into the well made in the flour and dry ingredients.
Quickly fold ingredients together with rubber spatula until almost combined.
Continue to fold in chocolate chips until a few wisps of flour remain.
Do not overmix.
Pour into a prepared tube pan and bake for 40-45 minutes or until done.
The cake will spring back lightly when touched and a toothpick inserted in the center comes out with a few moist crumbs attached.
Do not overbake.
Let sit on a wire rack for 15 minutes and then unmold cake.
Place right-side-up on a wire rack to cool completely.
To serve, combine powdered sugar and rum in a small bowl.
Place on a rimmed cake plate and glaze with the rum glaze.