Directions

1. Preheat oven to 350 degrees F (175 degrees C). Grease and flour a 9x13 inch pan. In a medium saucepan, combine 1/2 cup shortening, 1/2 cup butter, 3 tablespoons cocoa and 1 cup cola. Bring to a rapid boil and remove from heat.
2. In a large bowl, mix together the sugar and flour. Pour in the cola mixture and blend with a mixer. In a medium bowl, dissolve the baking soda in the buttermilk and add eggs, vanilla and sour cream. Mix well and then stir into the batter. Beat for 2 to 3 minutes.
3. Pour batter into prepared 9x13 inch pan. Bake in the preheated oven for 30 to 40 minutes, or until a toothpick inserted into the center of the cake comes out clean.
4. To make the Frosting: In a medium saucepan, combine 1/2 butter, 6 tablespoons cola, and 3 tablespoons cocoa. Bring to a boil, stirring constantly. When smooth, remove from heat and add confectioners' sugar and nuts. Beat until smooth, then pour over cake while both frosting and cake is still hot.