Chocolate Mousse Layer Cake

It's my birthday on Friday. I know it seems a little bit sad to bake your own birthday cake, but I had to make this cake. I couldn't get it out of my head all week. It's 6 layers of fluffy chocolate sponge cake sandwiched between thick layers of icing that tastes like chocolate mousse. When I was around 11-14 years old, every week my parents and I and would visit my favourite shopping centre in KL at the time (1 Utama) and my Mum would always buy me a slice of this layered chocolate cake from this bakery (which I can't remember the name of for the life of me). It was glorious. Thin layers of moist, light cake with a milk chocolate mousse icing. Equal ratios of cake to icing.

This week I suddenly remembered this weekly ritual of my past and I couldn't stop thinking about eating a slice of that cake. So I made it. And I ate it. IT WAS GLORIOUS. I might have gone a little overboard by making it 6 layers high, but I like my cakes sky high. I used a chocolate mousse icing recipe from the food dept. (if you aren't already following them, you should be) which looked pretty close to the icing I remembered from the magical cake of my childhood.

As per usual, there were a few mishaps in my kitchen. The first batch of icing totally effed up. The chocolate seized and the cream split. I had to make a mad dash to the supermarket to get more cream and butter (also gobsmacked that I managed to run out of butter, that hardly ever happens). The second batch I made nearly split again. I figured out it was probably because my cream was super cold and mixing it with the slightly warm chocolate/melted butter mixture was not the best idea. But it was still salvageable. At this point everything was covered in chocolate and I was extremely frazzled. So unfortunately this cake is a little messier than my usual layered-cake efforts. While I was taking the above photo, I pulled out that lovely tall slice of cake and then promptly dropped it. SPLAT. All I could do was sigh, take a photo of it and move on:

To be honest I was too impatient to eat the thing to spend a long time making the icing smooth or getting a great shot of the cake. It was for meeee. I topped it with a giant sized pack of Maltesers, to give it some crunch on top and because I love me some Maltesers. That first slice tasted so good. The sponge cake was the perfect cake to use with this icing, so light and soft and the whole combination wasn't heavy. It was exactly what I was looking for.

I did learn that eating this cake straight out of the fridge is not a good idea. All the butter in the recipe hardens and makes it quite dry when it's cold. You definitely need to let it come right back to room temperature before eating it, as recommended by the original recipe. I even reduced the amount of butter in the icing to make it a bit softer but feel free to use the amounts in the original recipe. I still think I could tweak this recipe to improve it, maybe brush some liquor on the sponge before layering it to make sure it stays moist, or play around with a different chocolate mousse icing recipe. But I'm pretty happy with it as is.

Chocolate Mousse Layer Cake

(chocolate sponge cake recipe adapted from my Tim Tam cake, icing recipe from the food dept.)

For the cake:
Note: Feel free to substitute with your own chocolate cake recipe, as this recipe is very delicate to handle. This cake is not recommended for those inexperienced with layered cakes.

8 large eggs

220g (1 cup) caster (fine granulated) sugar

130g (about 4.5 oz) cornflour (cornstarch)

70g (1/2 cup) Good quality cocoa powder

2 tbsp plain flour

2 tsp cream of tartar

1 tsp baking (bi-carb) soda

100g (7 tbsp) butter, melted and cooled

Grease well and line two 18cm (7inch) round cake tins with baking paper (if you use a larger tin (like a 20cm/8inch) you will end up with thinner cakes so you can probably only get about 4 layers). Preheat oven to 180°C (350°F). Whisk eggs and sugar in an electric mixer until thick and pale (at least 5-6 minutes, go nuts and don't underwhip). Sift over cornflour, cocoa, flour, cream of tartar and bicarb soda, fold in with spatula and make sure to get rid of any pockets of dry ingredients. Fold in butter, split equally between prepared tins. Bake in centre of oven until the centre of the cake springs back when lightly pressed (20-30 minutes). Turn onto baking paper covered wire rack and cool completely. (Can be baked the day before assembly and stored in an airtight container.) Use a long sharp knife to carefully cut each cake into 3 even layers, take care as the cake is delicate.

For the chocolate mousse icing:

400g (about 3.5 sticks) butter, softened

400g (about 14 oz) good quality chocolate (dark or milk, your choice. I used half dark half milk), melted and allowed to cool

600ml (about 2 1/2 cups) thickened cream

4 tbsp caster (fine granulated) sugar

Optional: Maltesers to decorate

Remove cream from fridge about 30 mins before starting. Place butter in a large mixing bowl and beat on high with an electric mixer until smooth and fluffy. Add cooled chocolate and beat until smooth. In a separate bowl, whisk cream and sugar until it just reaches soft peaks. Take cake not to overmix. Carefully fold cream mixture into chocolate mixture until combined. 

To assemble, place first layer of cake on your cake plate or stand, cover with icing and smooth with an offset spatula. Repeat with remaining cake layers and more icing. Crumb coat and cover entire cake with icing. Top with maltesers or another of your favourite chocolates. Can be served immediately (if in hot weather and the icing is very soft you can refrigerate it quickly to firm up the icing a bit but don't let it harden). Can be stored in the fridge overnight in an airtight container, make sure you return to room temp before serving or icing will be too hard (this may take a while, I had to warm my cake slightly in the microwave).