Preheat oven to 400 degrees. Gather your ingredients so that you have everything close at hand on the counter or table.Chop the pecans into small pieces.
Make the Cake Batter
In a small saucepan, melt the vegetable shortening and butter. Whisk in baking cocoa, then add water. Bring to a rapid boil. Remove from heat.
In a large mixing bowl, combine all-purpose flour, granulated sugar, baking soda, and ground cinnamon.
Stir in chocolate mixture. Add buttermilk, large eggs, and vanilla extract. Mix well.
Pour into a greased 10x15" jellyroll pan. Bake in preheated oven for 15-18 minutes or until cake springs back when touched.
Prepare Icing
To prepare icing, melt butter in medium saucepan on medium heat. Stir in baking cocoa, and whole milk. Bring to a boil.
Remove from heat. Stir in vanilla extract. Add powdered sugar and chopped pecans. Mix well.
Spread over warm cake. Serve with ice-cream. Serves 18-20.
Notes
*Unless otherwise indicated, all butter on this recipe site is salted.