Preheat oven to 180'C.
To make the cake, combine together the butter and sugar until pale and fluffy. Add in the eggs one by one, mixing well in between. Crack the eggs into a cup so you do not get any shell in the mixture!
Fold in the flour and cocoa powder as well as the red food colouring. Transfer lined baking tins. I used 21cm round tins. If you don't have four cake tins (I don't!) bake two for 25 minutes (or until a skewer comes out clean) and then another two afterwards. Leave all 4 cakes to cool completely.
I poured some sugar syrup into the cakes and wrapped them and left them in the fridge overnight, that way the cakes are much easier to apply icing to. Soaking the cakes in sugar syrup also makes the cakes more moist.
Using a round object that’s slightly smaller than your cake, (I used a cereal bowl) trim around the edges to create smooth outer edges. Place the off-cuts into a bowl.
To make the ganache for icing the cake, heat the cream in a pan on a low heat, once it has reached a level of almost boiling, pour the cream over the chopped white chocolate. Mix together and leave to cool.
To make the cake truffles, break up the off-cuts of cake to turn it into a crumb. Warm some jam up in the microwave and pour over the cake crumb. Mix together so it forms a dough-like consistency. Roll portions of the cake mix into balls. It can be any size you like but I went for a size that is slightly smaller than a golf ball. Leave in the fridge overnight to set.
Once your ganache has cooled, whisk it on a medium speed. This creates an icing just like buttercream, except it is much lighter and smoother-so it is easier to apply! The icing works because when you whisk it, the cream you have used will whip, essentially creating white chocolate flavoured whipped cream!
To assemble the cake, place some icing onto the cake, level out and add a small layer of jam onto it as well. Add another layer, and repeat until all four layers have been assembled. Crumb coat the cake by using more of the icing on the outside of the cake. If you have an icing turntable, use it at this point! It makes it so much easier to evenly apply the icing and ensure you have smoothed it out nicely. Once crumb coated, leave in the fridge to set. Ideally overnight, but you can get away with a couple of hours.
Once the crumb coat has set, use the remaining icing to ice the cake one more time. You are more than welcome to add more layers to get a crisp, white finish, but I was going for the "naked cake" look. Leave in the fridge to set. Again, overnight is great but a couple of hours is also fine.
To decorate the cake, melt the dark chocolate in a microwave or over a bain-marie, pour the melted chocolate over the top of the cake and work it to the edges so some of it begins to dribble down the sides. Leave to set completely.
Decorate however you wish, it’s entirely up to you, I used a little bit of glace icing to stick anything on top. It acts just like glue!