Don't be intimidated by length of instructions. Likely you will already know how to do this, but I wanted to give good directions, for those that don't. This recipe works when you need to make a moist, dense chocolate cake, but may not have enough baking chocolate or buttermilk on hand to do both cake and frosing. I find that this has been one of my most requested desserts! Pretty easy and flexible! Decorate with chopped nuts, shaved chocolate, chocolate chips,candy sprinkles, chocolate shots or twix candy bars around the side...possibilities are endless!
Preheat oven to 350F. Prepare four cake pans (or just use two, and wash to make next 2 layers) by spraying generously or greasing with butter flavored vegetable spray or shortening. Sprinkle flour on the bottom of the pan, and tip the pan to ensure that flour covers the bottom of the pan. Tip out any extra flour.
Make up one cake mix at a time. Pour 1 cake mix, 1 pudding mix, 1 1/4 C water, 1/2 cup melted butter and 4 eggs into mixing bowl. Beat well, until thoroughly combined, and about another minute.
Pour cake mix evenly between cake pans, and attempt to leave a little cavity in the center, so that you won't have as much to cut off to make layers even. Bake for 20 minutes (if your oven runs a little hot, check about 18 minutes. If you touch the top of the cake, it should bounce back and not leave an indentation, or a knife or wooden skewer inserted in the center comes out clean if cake is done. Allow cake to cool in the pan about 2 minutes, before removing to a cooling rack. Repeat the process, so that you have 4 layers for your cake. Cool to room temperature.
Wrap each layer separately and place in the freezer. Leave in the freezer long enough to freeze.
While cakes are in the freezer, clean up, and select any toppings you may want to use. Make the frosting. Prepare an area to frost the cake, by putting narrow sheets(about 3-4 inches wide)around the edge of a round plate. This will ensure that bits of frosting and decorations do not get all over the cake plate.
To make the frosting:
Whisk together the baking cocoa and powdered sugar. In a mixing bowl, beat butter until fluffy. Add powdered sugar mixture and evaporated milk alternately (ending with the sugar mixture)until you have a thick but manageable spreading consistency. Add the vanilla extract, mixing well.
Place layers (wrapped well) into the freezer and freeze. When cakes are frozen, remove and cut off the mounds at the top to be flush with the sides of the cake. Frost the top completely touching the edges (one layer at a time)fairly generously (if your frosting is not too thin, the cake will not slip). When you have finished, frost the sides of the cake thoroughly and decorate sides if you wish, or smooth gently and evenly with a paper towel to get a smooth finish. Finally,frost the top of the cake (generously if you want to do swirls, or a little less if you want a smooth top similar to fondant. Decorate as desired. Keep cake covered in the refrigerator for best results!