Preheat oven to 350 degrees. Grease and flour 3 round 9-inch cake pans.
For the cake, put flour, sugar, cocoa, baking powder, baking soda and salt in a bowl and mix well.
In a stand mixer, mix the buttermilk, oil, eggs, vanilla together. Slowly add in the mix of dry ingredients while the mixer is on low. Add the coffee and make sure everything is combined. Batter will be very thin.
Divide the batter evenly into the three prepared pans and bake for about 20-25 minutes or until a toothpick inserted in the middle comes out clean.
Turn the cakes out onto a cooling rack. While the cakes are cooling, make your filling.
For the creme filling,combine the milk and flour in a saucepan and cook over medium-low heat, stirring constantly, until the mixture thickens. It should get to be the consistency of runny pudding, which will take about 10-15 minutes.
Remove the mixture from the heat. It will continue to thicken as it cools. Press plastic wrap down on top of the flour mixture while it is cooling so it does not form a "crust" on top. Cool to room temperature.
While this is cooling, cream together the rest of the filling ingredients: the sugar, butter and shortening, on medium speed until fluffy, about 3 minutes.
Add the cooled flour & milk mixture and beat on high for 7 minutes.
Spread this filling between the cooled three layers of cake.
Now it is time to add your chocolate ganache! Put your chocolate chips in a bowl. Set aside. Heat heavy cream in a saucepan on medium/high until it comes to a boil. Watch it closely and stir often so it does not scald. Once it is very hot and near boiling, remove it from the heat and immediately pour it over the chocolate chips. Cover the bowl with a lid or plate and let the it sit for 3 minutes. Then, stir until the chocolate is completely melted and the mixture is smooth. Allow it to sit for about 20 minutes until the ganache thickens a bit.
Once your ganache is ready, pour it over the top of your layer cake. Use a spoon to spread it out towards the sides of your cake so it runs down a bit on the sides.
Decorate the top with Swiss Cake Rolls, if desired!
Store this cake in the refrigerator.
The calories shown are based on the cake being cut into 15 pieces, with 1 serving being 1 slice of cake. Since different brands of ingredients have different nutritional information, the calories shown are just an estimate.