Opera cake is a French cake. It is made with layers of almond sponge cake known as Joconde in French. The joconde is soaked in coffee syrup and layered with coffee buttercream and ganache and then covered with a layer of chocolate glaze. The richness of the cake makes it heavenly. This cake is an absolute treat for the chocolate and coffee lovers. A small portion is enough to fill your tummy. Ofcourse it has got an elaborate process in it’s making, but I promise, the end result is worth it. If It’s not practicable to do this all at once, you can prepare the joconde a day ahead and the icing the next day. That’s what I did. The Choctoberfest is really inspiring me to go beyond the limits and try out new things.
(for one Joconde,sheet pan size – 13×9 inches)
I made 3 sponge sheets
75 grams of Egg whites
20 grams of Sugar
60 grams of Almond powder
60 grams of Icing sugar
75 grams of Whole Egg
10 grams of Flour
15 grams of Melted Butter
150 grams of Dark chocolate
140 grams of Fresh cream
35 grams of Butter
250 grams of Butter (room temperature)
160 grams of Egg white
125 grams of Sugar 40 grams of Water
50 grams of Instant coffee powder
100 grams of Sugar
100 grams of Water
Basic sugar syrup
100 grams of Sugar
150 grams of Water
250 grams of Dark chocolate
40 grams of Vegetable oil
100 grams of extra Dark chocolate for coating the bottom of the cake.
Prepare the Joconde.
Line the sheet pan with baking paper.
Preheat the oven at 220 degree C.
Measure and keep all the ingredients ready.
Beat the egg whites until foamy, either in a stand mixer or in a hand held mixer. Add in the sugar and continue to beat until it becomes firm and glossy meringue. It might take up to 10 minutes or more.
Sift the almond powder, icing sugar and flour together into the large bowl with the whole egg. Beat with an electric mixer until smooth.
Gently fold half of the meringue into the egg mixture. Now add the remaining half and mix well.
Finally add the melted butter and gently mix with a spatula.
Spread the batter onto the baking pan. Use a palette knife of bench scraper to spread the batter.
Bake in the pre-heated oven for 10-12 minutes.
After baking, remove the cake immediately from the baking pan and let it cool down.
Take a piece of baking paper, large enough to cover the joconde. Keep it on top of the cake and flip it carefully. Now the bottom of the cake will be on top. Strip the baking paper carefully.
Prepare the second joconde and then the third.
Note :- Prepare all the sheet cakes separately.
Melt 100 grams of dark chocolate over double-boiler and pour it over 1 joconde and spread it immediately. Otherwise it will harden. Be careful not to overheat the chocolate.
Prepare the chocolate ganache. Heat fresh cream till boiling point and pour it over chopped dark chocolate in a bowl. Cover the bowl and let it rest for 5 minutes. Stir it with a wire whisk until the chocolate are completely melted and it’s well incorporated with the cream. Add softened butter and mix well. Set aside to cool.
Its time to prepare the buttercream. Its basically an Italian Meringue Buttercream. Heat sugar and water in a saucepan. Insert the tip of a candy thermometer in the saucepan.
Keep the egg whites ready in the bowl of a stand mixer. Make sure the bowl is completely dry, otherwise the meringue will be ruined.
Keep an eye on the sugar syrup. When the temperature reaches 230F, start whipping the egg whites. When the temperature of the syrup reaches to 240F, start pouring the syrup to the egg whites in thin streaks. The syrup will crystallize really quicky, so be careful it shouldn’t touch the metal bowl or whisk. Keep on whisking until the bowl is no more hot to the touch. If it’s hot then when we add the butter, it would melt and our buttercream will split and we won’t be able to use it. Normally for the Italian meringue, we start adding the room temperature butter at this point. But here I have whipped the butter separately and then combined the butter and whipped meringue with a balloon whisk. Make sure to whip the butter with an electric mixer until it turns to a whitish colour. Mix until its very well incorporated. My hand almost started to pain.
Next is the coffee syrup. Mix all the ingredients listed under the coffee syrup and bring it to boil. Set aside to cool.
Once the syrup is cooled, mix 2 or 3 tablespoon of it to the buttercream and mix well. Now our buttercream has become coffee buttercream. 🙂
Prepare basic sugar syrup by boiling water and sugar. Now mix the remaining coffee syrup to this sugar syrup.
So, we are done with the preparation part except the opera icing which we will do at the very end. Now comes assembling the cake. Which takes time as well.. Be very patient.
Assembling the cake. Remember step 2. We’ve coated one side of a joconde with melted chocolate. That side would’ve already been hardened. Now we have to flip it on to a cake board or a tray. Keep cake board/tray on top of the sponge sheet and flip it immediately which means the chocolate portion has gone to the bottom side. Now, brush the top of the cake with coffee syrup. The cake should be soaked in coffee syrup.
I did this almost 10 times to a single sponge sheet. Add half of the coffee buttercream and spread it evenly with an offset spatula. Top it with the second joconde and give a slight press with a baking tray. Again brush the sponge sheet with coffee syrup. Now pour the chocolate ganache and spread it evenly. On top of the ganache, put the third sponge sheet. Press lightly again. Brush the sponge cake with the remaining coffee syrup. Top it with the remaining coffee buttercream.(Reserve some buttercream if you want to do some decoration) Make sure this final layer of buttercream is smooth on top. Cover it with a baking paper and press lightly. Put it in the freezer for a couple of hours.
For the final layer of icing, melt the dark chocolate over a double-boiler. Add vegetable oil and mix. (I used olive oil, but next time I would use something which has got only a mild flavour) Take the Opera cake out of the freezer and remove the baking paper from the top. Pour the warm chocolate icing on top of the cake and immediately spread it with an offset spatula and tap the cake to smoothen the top before the chocolate hardens.
It’s better to cut the cake immediately, otherwise it would be difficult to cut it neatly once the chocolate hardens. Dip the knife in hot water, wipe it with a tissue and cut.