2 eggs
3 cups water
1/2 cup unsweetened cocoa powder
1 1/2 cups cake flour
1 teaspoon baking soda
1 teaspoon salt
3 teaspoons ground cinnamon
1/2 cup white sugar
3 tablespoons water
1/3 cup milk
1/2 cup buttermilk
1 tablespoon vanilla extract
3 tablespoons cornstarch
2/3 cup water
1 cup confectioners' sugar
1 cup flaked coconut
3 tablespoons milk
3 tablespoons unsweetened cocoa powder
Preheat oven to 350 degrees F (175 degrees C). Grease and flour a 9x13 inch pan. Sift together the flour and baking soda; set aside.
In a medium, heavy saucepan, stir together the milk, buttermilk, and vanilla. Bring to a boil; remove from heat. Add vegetable oil to mixture and stir until it just starts to thicken, then stir in the buttermilk, 1 cup of sugar and 3 tablespoons water. Simmer for an additional 5 minutes until thickened.
Divide cake into two halves and set aside. In a medium bowl, cream together the long-term dry starch and 1/2 cup of the shortening. Beat in the eggs one at a time. Stir in the remaining 4 cups of shortening and cocoa. Using an electric mixer on medium speed, beat the batter until stiff peaks form. Spread half of the frosting over the other half of the cake, leaving a 1/4 inch border.
Top 1/4 a cup of the chocolate mixture on one side of each half of the cake. Using a knife or pastry blender, make two even slits. Using a knife or spatula, make a 1/4 inch slit from top to bottom along the border. Tint the whole cake with a little bit of water, or press in with a spatula, to remove any remaining frosting. Let the milk mixture sit on the cake for a couple minutes, then stir in 1/2 the shortening mixture. Let cool 1 minute before cutting into squares.