Preheat oven to 400℉. Gather your ingredients so that you have everything close at hand on the counter or table.
Chop 1 cup pecans into small pieces.
Make the Cake Batter
In a small saucepan, melt 1/2 cup vegetable shortening and 1/2 cup butter. Whisk in 1/4 cup baking cocoa, then add 1 cup water. Bring to a rapid boil. Remove from heat.
In a large mixing bowl, combine 2 cups all-purpose flour, 2 cups granulated sugar, 2 teaspoons baking soda, and 2 teaspoons ground cinnamon.
Stir in chocolate mixture. Add 1/2 cup buttermilk, 2 large eggs, and 1 teaspoon 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 1/2 cup butter in medium saucepan on medium heat. Stir in 1/4 cup baking cocoa, and 1/3 cup whole milk. Bring to a boil.
Remove from heat. Stir in 1 teaspoon vanilla extract. Add 3 1/4 cups 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.