Let me start by saying that this is a very rich cake! Think layers of deeply dark and moist chocolate cake, luscious thick filling and a rich buttercream all working together in perfect harmony.
What makes a Bar One cake special is the Bar One chocolate. This is a much loved chocolate and why not add it to cake?
I have fiddled around with the filling until I managed to create a lush, thick cream that holds all the flavour of a Bar One chocolate but manages to transform into a silky, smooth concoction. A Bar One chocolate is quite chewy in texture and while this may work well in a bar of chocolate, it does not work well with cake. The addition of some marshmallows allows the melted chocolate to set and ultimately creates a thick, spreadable frosting.
The cake has a mega-punch of dark, unsweetened cocoa powder and is almost black in colour, and very moist. The chocolate buttercream also has more cocoa than normal and brings a pleasant bitterness to the cake.
Bar One Filling
- 4 x 55g bars of Bar One chocolate
- 50 g marshmallows
- 250 ml fresh cream
- Chop chocolate and marshmallows into small pieces.
- Add chocolate and marshmallows to a small heat-proof bowl and place over a small pot of shimmering water. (Bain Marie)
- Don’t let the water touch the glass bowl and over a low heat, stirring frequently, melt chocolate and marshmallows.
- Add cream to a small saucepan and bring to a shimmer.
- Pour over chocolate mix and using a whisk, mix until everything has melted into a smooth mixture.
- Cool and cover with a plastic wrap and refrigerate for a few hours. The mixture thickens and sets.
- Once the mixture has set, use an electric beater and beat till you get a thick and glossy icing.
Ingredients for Cake
- 75 g unsweetened cocoa powder
- 200 ml boiling water
- 3/4 tsp bicarbonate of soda
- 4 eggs
- 370 g light muscovado sugar or soft brown sugar
- 180 ml vegetable oil
- 200 g self-raising flour, sifted
Method to make cake
- Preheat oven to 180 degrees celsius.
- Grease and line the base of 2 or 3 x 20cm round baking pans.
- Whisk cocoa, bicarbonate of soda and boiling water until smooth. Set aside.
- In a large mixing bowl, whisk eggs, sugar and oil well together until smooth.
- Stir in flour and cocoa mixture and whisk until smooth and well combined.
- Divide equally between pans.
- Bake for 20 – 30 minutes until cakes are well risen, springy to the touch and coming away from the sides of the pan.
- Leave to cool in pans for a few minutes and then turn onto a wire rack to completely cool.
Chocolate Buttercream
- 250 g butter
- 2 1/2 c sifted icing sugar
- 1/2 c unsweetened cocoa powder
- 1 – 2 TB of fresh cream
- Beat butter with electric beater until pale and very smooth.
- Sift icing sugar and cocoa powder together and add to butter in 3 batches, beating very well in between each addition.
- Add cream to get a medium consistency icing. The cream also adds a richness to the icing.
Assemble cake
- If you have baked 2 x 20cm cakes, split each cake into 2.
- Sandwich all 4 layers together with the Bar One filling.
- Use the buttercream to generously cover and smooth the cake.
- Pipe small swirls of Bar One filling on top of cake.
