For the cake:
1 stick unsalted butter
1/2 cup vegetable shortening (can substitute the same amount of additional butter)
1 cup water
4 tablespoons baking cocoa
2 and 1/8 cups flour
2 cups sugar
1 teaspoon cinnamon
1/4 teaspoon salt
2 eggs
1/2 cup buttermilk
1 teaspoon baking soda
1 teaspoon vanilla (good Mexican vanilla, if you have it)
For the frosting:
1 stick unsalted butter
6 tablespoons milk
5 teaspoons baking cocoa
3 cups confectioner's sugar
1/4 teaspoon cinnamon
1/8 teaspoon salt
1 teaspoon vanilla (again, Mexican, if you have it)
1 cup chopped pecans
Directions
1. Preheat oven to 350 degrees. Spray a sheet cake pan, about 12" X 18" X 2", with cooking spray.
2. Place butter, shortening, water, and cocoa in a saucepan and heat just until butter and shortening are melted, stirring until smooth. Remove from heat.
3. In a large bowl, sift or whisk together the flour, sugar, cinnamon and salt. Stir the cocoa mixture into the flour mixture until combined.
4. In a medium bowl, whisk together the eggs, buttermilk, soda and vanilla. Pour this into the flour mixture and stir until very smooth and well-combined. Batter will be somewhat thin.
5. Pour batter into greased pan. Place in oven and bake for 19 to 20 minutes.
6. While the cake bakes, prepare the frosting: In a large saucepan over medium heat, stir together the butter and milk until butter is melted. Whisk in the cocoa, confectioner's sugar, and cinnamon until smooth and begins to bubble. Take off heat and stir in vanilla and pecans.
7. When the cake is done, remove from oven and place on cooling rack. Pour hot frosting evenly over hot cake. Let cool before cutting. Frosting will remain soft.
Cook's notes: I sometimes halve this recipe and bake it in a 13 X 9 cake pan (as pictured, above). Don't halve the frosting, though- it won't be enough to cover the cake.