To make the layer cake baking less time consuming and hassle, normally, I will bake one 8" and one 6" sponge cake together and then store them in the freezer. I will take it out when I need it but I normally try to clear them within a month. Separate the sponge cake baking and the icing/frosting work into two days helps to make the baking more enjoyable and less tiring.
If you would like to give this recipe a shot, please follow this link.
P.S. If you want to increase the amount of chocolate or filling, the max is 20% more as this cake is already quite chocolaty and moist.
Cheer! Enjoy baking!!!