Allow all of the ingredients to come up to room temperature. Preheat the oven to 400 degrees F. Grease at least three 9-inch round cake pans with shortening, or line with parchment paper, and set aside.
Make the chocolate icing first, place a large (heavy bottom) skillet or saucepan on the stovetop over medium-high heat. Add in the 3 cups sugar, 4 blocks unsweetened chocolate, 10 ounces evaporated milk, ½ cup butter, and 1 teaspoon vanilla. Whisk/stir to combine and allow the sugar time to fully dissolve and the icing to become smooth.
You may need to adjust the temperature to make sure the icing does not burn. Do not allow the icing to come to a high rolling boil. Once the icing ingredients are combined, adjust the heat to low and begin making the cake layers.
In a large mixing bowl, using an electric mixer, cream together the 1 ½ cups sugar and 1 cup butter. Then add in all 6 large eggs into the mixture at once and mix well until incorporated. Add in the 3 ½ cups self-rising flour and alternate with the 1 ¾ cups water, beginning and ending with flour. Mix in the 1 teaspoon vanilla extract and grab your cake pans.
Pour about ¾ cup of cake batter into each prepared pan and smooth (pat the bottom of the pans) until the batter reaches the edges. Place into the oven and bake for 7 to 10 minutes until golden brown and a cake tester comes out clean. I used 3 pans at a time and washed and regreased with shortening for a total of three times.
Once you remove the baked cake layers from the oven turn one layer onto a large plate and frost with icing from the center of the cake layer all the way to the edges until it covers the sides, then add another layer and frost again with the icing until you have a total of 9 layers.
When all of the layers have been stacked and frosted, spread the remaining icing over the top and sides to cover the entire cake. As the icing cools it will thicken.
Allow the cake to fully cool for about 10 to 15 minutes before slicing to serve. Enjoy!