Preheat oven to 350 degrees Fahrenheit.  In the bowl of an electric mixer, mix together sugars, shortening and eggs.  In a separate bowl, stir together flour, baking soda, cinnamon and salt.  Pour boiling water over oatmeal in a separate bowl and let stand for 10 minutes.  Add flour mixture to sugar mixture and mix until combined.  Add oatmeal and mix until combined.  Pour into a greased 13" x 9" cake pan and bake for 30-35 minutes, or until toothpick inserted into center comes out clean.

 

Let the cake cool, and then prepare the topping: Stir all ingredients together in a sauce pan over medium heat until butter is melted and mixture is well-combined.  Pour over cake and spread evenly.  Put cake under a broiler and broil until coconut is brown, but not burned.  I set the timer for one minute and keep checking it so it doesn't burn.  The broiling is crucial and lends a wonderful flavor.