Preheat oven to 350 degrees F. and prepare a 9 X 13-inch baking dish by spraying it with cooking spray.
In a small bowl, whisk together the cake flour and cocoa.
In a mixing bowl, cream sugar, butter and applesauce until light and fluffy.
Add eggs and vanilla and mix until thoroughly combined. It will appear curdled in the first few minutes, but will become smooth.
Add the flour mixture and mix.
Add in 2/3 cup pecan pieces and the coconut. Mix until well combined.
Pour into prepared baking dish.
Bake for 30 - 35 minutes, until a toothpick inserted into the middle comes out clean.
In a clean mixing bowl, combine the butter, cocoa, and vanilla and mix.
Gradually add the confectioners' sugar.
Gently pour in the half and half, and mix until smooth.
While the cake is hot, spread the jar of marshmallow cream evenly over the top using an offset spatula.
Cover with icing.
Sprinkle remaining 2/3 cup pecan pieces over the top.
Allow to cool before slicing.
I was impatient and sliced into the cake while it was still warm which allowed the marshmallow cream and icing to flow off the cake and into the pan. I suggest allow the frosted cake to cool completely before serving or to refrigerate and allow to set.