This cake was EPIC. I have never taken on something with so many different components but it was totally worth it! I made this as an Easter treat but it made so much I have been eating it for the last week. The recipe comes from my baking text book and so the original recipe is a commercial size batch of cake. Even after I halved the recipe it still made 3 bar cakes. Two I covered in the Glacage Opera but one I left plain and that one was probably my favourite.
I wanted to try this cake because it seemed a bit Tiramisu-like and the layers looked fantastic. This is the kind of cake I would like to have in my own bakery one day. It was just simply divine to get all that coffee and chocolate flavours together with the creamy buttercream and spongy biscuit all in one bite... HEAVEN!
The cake covered in the chocolate was just a bit too much chocolate (I didn't know it was possible?!) but still delicious of course. The chocolate ganache I made was a bit runny and oozed out the end in a delicious kind of way. My guilty pleasure was taking a piece of frozen cake and microwaving it just until the ganache was runny and eating it like that, mmmm so good!
Opera Cake
Adapted from Advanced Bread and Pastry: A Professional Approach
What you will need
Biscuit Viennois
225g almond meal
225g icing sugar
100g egg yolks
150g eggs
400g egg whites
40g caster sugar
90g cake flour, just use plain flour but replace a spoonful with cornflour
90g pastry flour, strong flour or '00' flour
Coffee Buttercream
250g caster sugar
50g water
150g egg whites
300g butter
30ml coffee extract
Coffee Soaker
1l strong coffee
350g caster sugar
30ml coffee extract
Chocolate Ganache
500ml cream
500g chocolate melts
Glacage Opera
325g dark compound chocolate
125g chocolate melts
45ml oil
What you will need to do
To make the biscuit viennois, preheat the oven to 205*C and line three identical baking trays with baking paper. I used my cookie trays that have a good 2cm side on them and they were fine, the biscuit doesn't rise too much. Start by sifting the almond meal and icing sugar together and set aside. Sift together the cake flour and pastry flour and set aside. Whip together the almond mixture, egg yolks and eggs until tripled in volume. In a separate bowl whisk together egg whites and sugar to create a merengue. Fold the merengue into the almond mixture and then fold in the flour mixture. Evenly distribute the mixture between the three baking trays and spread out evenly. Bake for approximately 7minutes or until cooked through. Remove from trays after baking so as to not continue cooking further.
To make the coffee buttercream, dissolve the sugar in the water in a saucepan over low heat. In a stand mixture, begin whisking the egg whites to stiff peaks. Once sugar reaches boiling point, remove from heat and pour slowly down the side of the mixer bowl while still whisking egg whites. Continue to whisk until thick and shiny. Remove whisk and replace with paddle attachment. Beat for 10 minutes or until completely cooled. Begin adding the butter in small cubes beating well after each addition. Once all the butter has been added, you should have a thick buttercream. Beat in the coffee extract until combined.
To make the coffee soaker, dissolve the sugar in the coffee and add the coffee extract.
To make the chocolate ganache, in a saucepan bring the cream to boil. Remove from heat and add chocolate. Stir until melted then set aside. The ganache needs to cool and thicken to a spreadable consistency.
To assemble the cake, place one tray of biscuit viennois in the bottom of a large baking tin with sides at least 10cm high. The biscuit viennois must fill the entire base of the tin, mine were a bit large and I had to trim the edges to fit.
Pour a third of the coffee soaker over the base trying to get an even coverage. I used a small measuring put to pour over and then a pastry brush to fill any visible gaps. You can see in my photos that some parts had more soaker than others, it can be hard to determine how evenly it has distributed.
On top of this, spread 2/3 of the coffee buttercream evenly across. Place the second biscuit viennois on top of this and pour over another third of the coffee soaker.
Spread the chocolate ganache over this as evenly as possible. My ganache was a bit runny still and you can see in the photo below that it ran down the sides a lot.
Place the last biscuit viennois on top of the ganache layer and pour over the rest of the coffee soaker.
Spread over the last of the coffee buttercream on top and pace cake in the freezer until needed.
An optional finish for the cake is the Glacage Opera. To make it simply melt the chocolates together and then add in the oil. You can pour it over the whole cake or just make a nice design on top with it.
