Preheat oven to 350ºF. Grease and flour 3 round 8-inch cake pans.
Add the flour, sugar, cocoa, baking powder, baking soda and salt in a bowl and whisk well. 1 3/4 cups all-purpose flour, 1 3/4 cups granulated sugar, 3/4 cup unsweetened cocoa powder, 1 teaspoon baking powder, 2 teaspoons baking soda, 1 teaspoon salt
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. 1 cup buttermilk, 1/2 cup vegetable oil, 2 large large eggs, 1 teaspoon vanilla extract, 1 cup freshly brewed strong hot coffee
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. 1 1/4 cups 2% milk, 5 tablespoons all-purpose flour
While this is cooling, cream together the rest of the filling ingredients in a large bowl: 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. 1 cup granulated sugar, 1/2 cup salted butter, 1/2 cup vegetable shortening
Spread this filling between the cooled three layers of cake. Now it is time to add chocolate ganache! Place the chocolate chips in a bowl. Set aside. Heat heavy cream in a saucepan on medium heat until it is very hot and near boiling. (You can also heat it in a microwave). Then 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. 12 ounces semi-sweet chocolate chips, 1 cup heavy whipping cream
Once the ganache is ready, pour it over the top of the 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.
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Notes
The calories shown are based on the cake being cut into 12 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.