It was my mom’s birthday this past week and what cake did she request? The one and only Opera Cake of course. I knew that this was a long and laborious cake to make, and I expected to spend around half a day on it. Just bake the Joconde cake, some ganache, buttercream, and ta-da! Except it was not.
It definitely took me a whole day. It was also daylight savings on top of that, so I felt like I was losing an hour every single hour. A large chunk of that time was spent calculating, and figuring out how I would go about things, so hopefully you won’t have to slave away for a whole day since I’m telling you how things are going down.
The first issue I ran into was the size. Most of the recipes I looked at called for 6 whole eggs and 6 egg whites. I wasn’t quite looking forward to using a dozen eggs on one cake so those recipes were out. Turns out, the cake that you make using a dozen eggs is gigantic. It wasn’t practical for a birthday cake, and I found that 3 eggs and 3 egg whites was the perfect amount/size. I have an 11×18 inch baking sheet, so I wanted to make a 11×6 sized cake, after cutting up the cake slab into three pieces (the cake will be a little smaller after the edges are cut off for a neater presentation).
I also realized that regular grounded espresso WON’T dissolve. It’ll stay grainy. Forever. So if a recipe says instant… use instant espresso. I have the nespresso capsules at home, so I broke one open to make the coffee syrup. As a syrup, I just decided to use it (since the nespresso ones are actually incredibly fine), but for the buttercream, I had to strain out the grinds and use the leftover liquid. (which worked surprisingly well)
So what exactly is an Opera Cake?
If you love chocolate and coffee, this cake is for you.
Here’s the breakdown, going from bottom to top: chocolate, joconde sponge cake, coffee buttercream, joconde sponge cake, ganache, joconde sponge cake, coffee buttercream and finally a mirror glaze. 8 layers of goodness. But even after slaving away at it for a whole day (don’t even get me started on how I didn’t even get to eat lunch…), I thought it was totally worth it. Keep in mind, though – like most things, the cake tastes better after spending some time in the fridge. The flavors develop better, and yes, I know it’s so hard to wait after watching into come into fruition from nothingness, but do it. Do. It.
Compared to the other recipes, I also reduced the amount of sugar, and the cake still tasted really sweet, so I would recommend doing so as well. I found that it was just easier to make all the component separately, and then just compile all of it together at the end.
Joconde Sponge Cake
115 g almond meal (alternatively, you can just use 115 g of blanched almonds and grind it up)
80 g powdered sugar
25 g cake flour
3 whole eggs
3 egg whites, room temperature
15 g white sugar
50 g melted dark chocolate, preferably Valrhona
Preheat oven to 400 F
1. In a medium sized bowl, whisk the 3 whole eggs together well. Really go for it. Sift in the powdered sugar and the almond meal, and continue mixing until mixture is smooth and light. Finally, sift in the cake flour, and stir that into the egg mixture until it is just mixed well. Set aside.
2. In a mixer with the whisk attachment, add the egg whites. Make sure the bowl is impeccably clean and dry. Start beating the egg whites on high. When the egg whites start foaming, slowly pour in the white sugar. Continue beating (you may want to turn the mixer to a medium once soft-medium peaks are formed) until medium-stiff peaks are formed.
3. Using a spatula, transfer one third of your meringue into your egg-almond mixture. Mix this well, but don’t go too crazy. Now pour your entire egg mixture back into the bowl containing the meringue. At this point, be gentle. You don’t want to deflate the egg whites so much that they won’t rise, since the air is the only leavening agent in the cake. Do, however, mix it well, as you don’t want any chunks of only meringue or chunks without it. When you pour your mixture into the baking pan, you can check as you pour for any missed chunks.
4. Line a 11×18 inch baking sheet with parchment, or just place a silpat on the bottom(as I did). Pour your batter into the baking sheet, and smooth it out. You don’t want to mess with the batter so much that all the air leaves, but you want a smooth cake. I used one of those wooden crepe spreaders, and it worked wonderfully.
5. Tap the baking pan on the counter a few times, and then put it in to the preheated oven.
6. Bake for around 15 minutes, or until the top is a light golden brown color. The edges will brown quicker, but that’s not an issue since you’ll be cutting those pieces off.
7. Let the cake sit for around 10 minutes, or until it somewhat cool, before messing around with it, since it’s more fragile when it’s warm.
8. Once you’ve removed the cake from the parchment, cut the cake up into 3 equal pieces (around 6×11 each).
9. On one of the slices, pour the melted chocolate (you can pour it hot) on only one side of the cake. It should fit perfectly. Smooth out the chocolate, and then throw that slice into the freezer for 5 minutes, to harden the chocolate. This is the chocolate layer that goes on the very bottom of the cake. Cover the rest of the cakes in parchment, to prevent drying.
10. Remove the slice of cake with the hardened chocolate from the freezer, and cover.
Coffee Syrup adapted from The Splendid Table
1/2 cup water
1/4 cup sugar
5 grams instant espresso
1. Mix all the ingredients in a small saucepan, and bring to a boil. No need to thicken it, because it will thicken as it cool. Let the syrup cool.
1 1/2 sticks (12 tablespoons) room temperature butter
5 tablespoons sugar
20 g water
2 egg yolks
2 tablespoons instant espresso
2 tablespoons boiling water
1. In a separate bowl, beat the butter using a spatula until smooth, and all the chunks are gone. Set aside.
2. Mix the the espresso and boiling water together until espresso dissolves. Set aside and cool.
3. Add the egg yolks into the mixer with a whisk attachment, and start beating at a medium speed. Do this until the yolks are light and creamy.
4. In a small saucepan, add the sugar and remaining water. Cook it until the mixture reaches 115 F. This should be done around the same time the egg yolks are beating.
5. Once the sugar has reached the right temperature, slowly pour it into the egg yolks (with the whisk going at medium) at the edge where the yolk meets the bowl. Once all of it has been poured in, continue beating on medium-high until the yolk has cooled down to room temperature.
6. Once the yolk cools, start beating in the butter a little at a time. Add each new addition after the previously added butter has already been fully incorporated. You should see the mixture thicken and become stiff after a few additions of the butter. Add in the coffee a little at a time, tasting as you go (my favorite part) to determine how strong of coffee you want your buttercream to taste.
7. If your buttercream is not stiff enough, throw it in the fridge for 10 minutes, but if it is already at a good spreadable consistency, just leave it out.
Dark Chocolate Ganache
5 ounces chopped dark chocolate, preferably Valrhona
125 g heavy cream
1. In a small saucepan, heat the heavy cream until the cream is bubbling.
2. Remove the pan off the heat, and add the chocolate. Let it sit for 30 seconds, and then slowly stir until ganache is smooth.
3. Pour ganache into a bowl, and let it cool until a spreadable consistency.
20 g cocoa powder, preferably Valrhona
30 ml water
25 g heavy cream
30 g sugar
1. Combine all the ingredients in a saucepan, and bring to a boil. Let the glaze cook until it thickens slightly, but keep in mind that the glaze will thicken as it cools.
Assembling the Cake
For the first slice of cake, place it chocolate side down. Generously brush on the coffee syrup until the entire surface is covered. Add on half of the amount of buttercream and spread it evenly. The thickness of the buttercream should be the same as the cake (around 5 mm). If you look at at it from the side before cutting the sides off, it’ll look thinner than it actually is, but just try and spread it as evenly as possible. Add the second layer of cake, and brush with syrup again. This time, spread the ganache (same thickness as the buttercream/cake) evenly. Add the final slice of cake, and repeat brushing the syrup. Add the rest of the buttercream and once it’s completely flattened, cover and stick it into the freezer for 20 minutes. You need to cool the cake because the glaze will be warm when you pour it on, and you don’t want to melt the buttercream.
Pour the glaze onto the cooled cake, and use a spatula to smooth out the top if need be. Return the cake to the freezer to allow the glaze to settle.
To cut the cake, use a hot serrated knife to cut through the cake. Serve at room temperature. And now, go take a nap.