Technical Bake #25: Opera Cake

Hello and Happy Halloween, Friends and Fellow Bakers! Spooky season is trundling along so I decided to include the Opera cake (recipe here) this month, as featured on Season 1, French Patisserie week of GCBS. Opera cake is a historical bake dating back as far as the 1890s. My rudimentary online research has differing stories, but the widely held belief is it is named Opera cake because the layers resemble the appearance of the interior of the Paris Opera House. It is a complex cake built of seven incredibly thin layers (mine was less than 2 inches tall). The presentation is meant to be perfectly clean 90 degree angles all the way through and around with a completely precise and flat hardened chocolate glaze on top. Natch. 

I decided to include this in my October bakes because what could be more goth and spooky than the Phantom of the Opera and his whiny crybaby misogynist nonsense? NOTHING. I had tons of fun listening to the Phantom and other, better more authentic, opera while I was making this even though it isn’t quite picture perfect.

This is the classical version of the Opera cake, the layers being: 

• Chocolate: the recipe called for pate a glacer which is similar to tempered chocolate. I was unable to source pate a glacer so I just used plain ol’ chocolate
• joconde sponge soaked with coffee syrup
• Coffee-infused italian buttercream icing
• another layer of soaked joconde
• chocolate ganache
• More soaked joconde
• Italian buttercream again
• Chocolate glaze

This was also the largest recipe I have completed for this project (other than the Rugelach, but I doubled that recipe to make it larger on purpose. This recipe was huge as-is). It was a real marathon to get done and I will admit I was pretty wiped out the next day. Allow me to give you a quick summary on these cake specs to give you an idea of the scale. As a whole, this recipe included:

• 2 full size sheets of cake. I had to buy full size sheet pans, which I was actually pretty stoked about. Bonus!
• 10 (!) whole eggs PLUS 7 egg whites -> yes, that is a total of 17 eggs for this bad boy
• ¾lb of butter (there was actually a surprising amount of extra buttercream leftover, so not all of it went into the cake)
• 650g of chocolate

If nothing else, we know we can count on France to be extra AF. 

I didn’t have any major challenges with this bake, just the usual little baking perfectionism points. My sponge was a bit thin on the sides so it had some uneven baking on the bottom, but that was pretty undetectable once served. 

I noticed during the episode that every contestant except for one was told they did not put enough coffee syrup in the sponge. I tried to take this criticism as a lesson, but I was probably a little light-touch with it also. TOTALLY UNDERSTANDABLE. After putting so much effort into an absolutely MASSIVE sponge, over soaking it until it is mushy would be a real travesty. I felt like my cakes were well soaked when I assembled them, but after reviewing the CBC photos of their exemplar cake, I think their sponge looks way darker than mine, so I could have probably added more syrup. I felt like the taste was coffee-forward, so I’m not sure.

I had my usual moment of panic where I thought I broke the Italian buttercream. I have made meringue/egg based buttercream twice for this project now (see my posts about Marjolaine and Strawberry Roulade to learn more about that), so I feel more comfortable with the method than I used to, but it is still a test of nerve every time. It all came together in the end, but there was definitely a moment of silence as I prayed over my running mixer, as all desperate and anxious bakers worth their salt are wont to do.

Adding to the complexity of the buttercream was the call for 2 tbsp of coffee extract. I couldn’t find extract, so I used bakery emulsion. I have never worked with bakery emulsion before. My understanding is emulsion is supposed to be more versatile and better tasting than extract because it is water-based. I didn’t want to risk breaking the buttercream after I already felt it was dicey by adding WATER to it, so I only put one tbsp of the emulsion in and left it at that. I know better than to try and test the generosity of the baking gods. I think it turned out, as I said the overall eating experience was coffee-forward, which I think is the goal here. 

Finally, I struggled a bit with the final glaze. I should have re-warmed it before I poured it, and I realized that too late. I tried to spread it, which you are NOT supposed to do, and that made it even worse. So I threw together a little more glaze and dumped it on top. The result is I got a much smoother look than the first attempt, but I didn’t get the nice, perfectly even, smooth like glass look. I think I made up for it a bit because my cake writing looks pretty good, and of course I had nice clean edges because I know what I’m doing with a knife. Those elements are part of the presentation too, but I admit they don’t carry as much weight as the glaze. 

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Step 1: Joconde

Once again we are met with this basic white sponge as a cake base. This is a classical preparation with almond flour. Half of the eggs, sugar, and almond flour are whisked on high until they are doubled in volume. The remaining eggs are added and the whisking continues until the batter is highly aerated. 

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The batter base is put aside and then additional egg whites and sugar are beaten to stiff peaks making meringue. The meringue is folded into the batter base and then turned out to pans. A reminder that we are talking about 6 eggs plus 7 egg whites, FULLY AERATAED, making for two large-ass sheet pans full of cake.

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Step 2: Chocolate Ganache

Not every element of this cake was a workout. This is standard ganache, where hot cream is poured over chocolate and stirred. Lovely.

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Step 3: Coffee Syrup

This and the ganache are the simplest components of this bake. Sugar, water, and coffee extract (or in my cake, bakery emulsion) are brought to boil and that is all there is to that.

Step 4: Italian Buttercream

Here comes the scary stuff. Egg-based buttercreams require sugar work and mixer management and you have to do both simultaneously. There is no way to do one and then the other to cover your ass and it is terrifying. In the case of Italian Buttercream, whole eggs are used (as opposed to French Buttercream which is egg whites only). 

Sugar is brought to temperature on the stove. My increased comfort level with sugar work is one of the best things that has come out of this project, I must say. You can never get too comfortable, though! Even experienced confectioners have sugar crystallize if they aren’t paying attention. With that being said, I have found some little things that help to ensure success. I put a lid on the pot until the sugar is fully liquefied. The steam from the boiling solution helps dissolve the little sugar granules on the sides of the pot that can cause crystallization. It slows down the pace a little bit, which makes the mixer management a bit harder and I am not winning any efficiency awards, but at least I can pull off this kind of syrup on the first try now. I also find it helps to put the pan on a burner that is wider than the base of the pan. I noticed in other bakes where I had to re-do my sugar that it was because it wasn’t heating as quickly on the edges when I had it on a smaller burner. In other cooking applications, this doesn’t really matter because you can stir the mixture to distribute the heat. Stirring sugar is a surefire way to wreck it, so larger burner it is!

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While the sugar is heating, the eggs are beaten until they are well aerated. If the eggs come up to volume well before the sugar reaches temperature, it is best to leave the mixer running on low so the eggs don’t separate and/or deflate. The best way to approach this is to coordinate when you start mixing with the temperature of the sugar as it rises. I am getting better at this, but I still don’t feel terribly confident. Practise makes perfect!

Once the eggs and sugar are ready, the sugar syrup is streamed into the eggs while the mixer runs on high. The hot sugar gently cooks the eggs which makes the buttercream more stable at room temperature. The mixture is whipped until cooled to room temperature. The butter is gradually incorporated while the mixture is continuously whipped on high. Once the butter is fully incorporated and the mixture comes together, the coffee flavouring is added.

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Step 5: Chocolate

I am condensing two steps here because as I said, this cake was a marathon and so is this post. The remaining two elements are chocolate chablon and chocolate glaze, which are almost the same thing. The chocolate chablon was meant to simply be melted pate a glacer, but as I mentioned, I could not source this for the life of me. I substituted melted chocolate and it was just fine. 

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The glaze was different types of melted chocolate and vegetable oil melted together. Very simple and easy. Once again I couldn’t find the exact chocolates called for in the recipe, but I made do with what I could find and my glaze consistency turned out fine. I just had trouble pouring it because it had cooled too much. 

Step 6: Assembly

As I already outlined the layers of this cake above, I will summarize the assembly of the layers as briefly as I can.

The two sheets of sponge are cut in half. Three of these layers are used for the opera cake. I used my leftover half-cake to make a little ¼ scale version using the leftover components, which was very cute and a great little gift idea.

The chablon is poured onto one layer of cake and then chilled. The instructions had all this detail about flipping the cake and using the parchment side and it was very complex. I am not convinced this was strictly necessary, but I followed the steps as written.

The cake is flipped again so the chablon is on the bottom, then the cake is soaked with coffee syrup. A thin layer of buttercream is spread on the cake and that is topped with the next layer of cake. The second layer of cake is soaked with coffee syrup and that is topped with ganache.

The ganache is topped with the third and final layer of cake which also gets soaked with syrup. This layer gets another thin spread of buttercream. Now here is where I would do things slightly differently next time and the instructions could have been more detailed. The recipe simply says to put an extremely thin layer of buttercream on and then chill the cake before pouring the glaze. I now realize what I should have done was tried to ensure the buttercream was as smooth as possible before pouring the glaze by putting parchment on top of it after it was chilled and then smoothing it with my hands. Cake decorating 101, but I didn’t come up with that until it was too late.

If I had smoothed the buttercream and re-heated the glaze before pouring, I am confident I would have achieved the perfectly flat presentation on top. Lesson learned! Anyway, once the glaze is on, a long, sharp, heated knife is needed to trim off the sides of the cake in order to get the full dramatic effect of all the layers presented with nice, clean edges. A reserved portion of glaze is used to write the word Opera on the cake, and woop, there it is.

Gallery

My mental and physical labours were well worth it for this one. This was a decadent and delicious cake that disappeared when I brought it to work. It will not surprise my regular readers to hear that I personally did not care for this cake. It was too rich and had too much chocolate in it for my taste, but my opinion is unimportant. Everyone who tried it loved it, as far as I know. I would make this again for a party, for sure. It’s a real show stopper. I also like how the final presentation depends as much on cake decorating skills as on knife skills. It is a bake for those of us who are also a little more culinary. Onward we go!

Hey, bakers! Check out my BAKER’S PANTRY index if you want to deep dive on specific ingredients when attempting this bake for yourself