Preheat oven to 350°F/180°C (160°C fan oven), grease and line two 8” baking pans with parchment paper and set aside. I like to use the pre cut parchment circles for convenience.
In a medium bowl, combine flour, cocoa powder, baking powder, baking soda, salt and set aside.
In a large bowl, beat butter and sugar until smooth and creamy (3 minutes), then add eggs and vanilla and beat on high speed for 2-3 minutes, until pale and fluffy
Add half the flour mixture and half the buttermilk and beat, and repeat until flour and buttermilk has been used up
Add the coffee and mix again until smooth.
Divide the batter between the two prepared pans and bake for 35 minutes, or until a toothpick inserted in the center comes out clean
Allow to cool 5 minutes in the pan, then turn out onto a wire rack to cool completely.
Cream filling:
In a medium saucepan, whisk together the flour and milk over medium heat and bring to a simmer, stirring constantly until it’s thick like roux. Remove from heat and stir in the vanilla.
Allow the mixture to cool completely, stirring every few minutes.
In the bowl of a stand mixer, whip the butter and sugar until pale and fluffy, about 5 minutes.
Add the cooled milk mixture and whip again until white and fluffy, about 3-4 minutes; set aside
Ganache:
Heat heavy cream until steaming (not boiling! As it might separate), add the chocolate to the cream and allow to sit for 2 minutes. I like to use a little jug to easily pour the ganache over the cake.
Carefully stir until the mixture is smooth and no lumps remain.
Stir in the corn syrup and allow to cool to room temperature (at least 30 minutes)
Assembly:
Level the cooled cakes if necessary (but this chocolate recipe makes even cakes, maybe if the temp of the oven is too high, people can get domed cakes), keeping them on the wire rack, place wire rack overtop of a baking sheet
Add all the cream filling to the top of one cake and smooth it into an even layer, top with the second cake layer, then level off the cream from the sides (this will make the ganache sit nicely and the cake will have smooth edges). and place into fridge to chill for at least 30 minutes.
Pour the cooled ganache over the cake, you can use as offset spatula to gently guide the chocolate to all sides of the cake, and to smooth the sides slightly
Place cake into the fridge to set the ganache, about one hour. Slice and serve.
Video
Notes
Slice After Chilling: If you try to slice this cake when it's not chilled, the cream filling will run out! Slice it after it's been chilled.
Serve at Room Temp: While you should store this cake in the refrigerator, and slice it while it's cold, wait to serve the slices until they have sat at room temperature for 10-15 minutes.
Avoid Overmixing: an overmixed cake batter will turn into a tough cake after baking. Mix ingredients just until combined.
Use a scale: To be sure that your layers are all the same size, use a kitchen scale to weigh the three bowls of batter.
Level if needed: If your cakes come out domed you may need to level them using a serrated knife. This recipe shouldn't dome too much though!
When Making Ganache, be sure not to stir it too vigorously. This can create air bubbles and keep you from getting the super smooth coating you're looking to create. It's also important to let the ganache cool to room temperature. It's too liquidy when it's hot.
To Store: Keep Ding Dong cake covered in the refrigerator for up to 3 days. You can also store individually wrapped slices of cake for up to 3 months.