Preheat oven to 350 degrees F (175 degrees C). Grease and line with parchment paper one 9 inch round cake pan.
Cream shortening, add white sugar gradually and cream until fluffy. Blend in the well beaten eggs.
In a separate bowl, slowly add hot water to cocoa and mix until smooth, dissolving cocoa completely.
In a third bowl, sift together the flour, salt, baking soda, and baking powder; add to creamed mixture alternately with the cocoa mixture. Blend in vanilla. Pour batter into one 9 inch round pan.
Bake at 350 degrees F (175 degrees C) for 30 to 35 minutes or until cake tester comes out clean. Let cake cool then ice with Lemon Icing.
To Make Icing: Combine confectioner's sugar with enough lemon juice to make the icing spreadable without being runny or stiff (about 1/4 cup). Stir in the grated zest. Pour icing over top of cake. See the full moon.
