When our friend Traci commissioned a surprise birthday cake for her significant other, Dan, she requested something chocolate.
So I started flipping through my cookbook collection looking for inspiration for chocolate, chocolate, and more chocolate.
This was no time for restraint.
Special occasions call for special cakes. And this would be a special cake.
I knew I wanted to take an expansive, maximalist approach. This was going to have many layers and textures and chocolate varieties. So I turned to some of my favorite baking books in search of components to build the cake that was forming in my head.
I started with a cake called the Dame Chocolat from Karen Krasne’s book Extraordinary Cakes which involved chocolate cake and semisweet ganache and a bittersweet chocolate mousse. But as it appeared in the book, it wasn’t quite big enough of tall enough or complex enough for what I was going for.
I had read about caramelized white chocolate on Food 52 and on David Lebovitz’s blog a while back. It had been rolling around my head for months, and I knew I wanted to incorporate it in some way. At first I thought I’d go with a mousse, but the more I thought about it, I decided I didn’t want to mask the flavor of the caramelized white chocolate with eggs. I recalled one of Alice Medrich’s cake components from her book Bittersweet (since updated and reprinted as Seriously Bitter Sweet), a whipped ganache that I had previously used in a chocolate roulade.
Like most classic ganaches, it is made of chocolate and cream. I thought the cream would carry the caramelized white chocolate flavor nicely without overpowering it. But I was afraid that it might be too sweet.
Caramelized white chocolate has a much deeper flavor than the white chocolate we all know. It’s more like dulce de leche or caramel than white sugar, but still, this was a party for grown ups and I wanted to keep the flavor profile in balance, so I stole an idea from another one of Krasne’s cakes, one she calls the Bonaparte, which has a layer of mousse with salted bittersweet chocolate bits in it.
I thought the salt and the bittersweet chocolate would cut the sweetness of the caramelized white chocolate nicely. So I melted some bittersweet chocolate, spread it out thinly, and sprinkled it with big flakes of Maldon sea salt, which I rolled into the soft chocolate, and then chilled until it was firm enough to break into shards. I kept those shards chilled until the ganache was whipped and they could be folded in to create little dark salty flecks in the caramelized white chocolate.
I then had a cake that consisted of four layers of flourless chocolate souffle cake, a chocolate soak for the cake layers, a light and airy whipped caramelized white chocolate ganache with salty chocolate shards, four layers of bittersweet chocolate ganache, two layers plus and outer coating of bittersweet chocolate mousse, all topped with a shiny chocolate mirror glaze.
It no longer felt like the Dame Chocolat, or even the first working title I had for it, the Nouveau Grande Dame Chocolat, it had evolved and expanded to thirteen layers. As an inveterate book nerd, I am unable to think of the number thirteen without thinking of Wallace Stevens’ blackbird. And so this became, perhaps predictably, my Thirteen Ways of Looking at a Chocolate Cake.
This is, if you’re counting, a takes-3-or-4-days-to-make cake, depending on how much time you’re willing to spend each day. Caramelizing the white chocolate is a simple but slow process. It needs to spend time in a low oven and get stirred frequently. It can be made several days in advance and should be incorporated into the whipped ganache base at least a day before assembling the cake.
The chocolate soufflé cake requires melting chocolate and separating eggs and whipping them and combining everything together with a delicate hand.
It can be made a day before assembling the cake.
The salted chocolate shards can be made several days in advance as long as they are kept chilled. The chocolate soaking syrup can be made in advance as well.
But the bittersweet chocolate mousse and the dark chocolate ganache (it can be bitter- or semisweet) should be made on the day you assemble the cake. Which should be a day before you want to serve the cake, because after it is assembled, the whole thing needs to go into the freezer overnight and then get topped with a final layer of ganache and mirror glaze and thaw for a few hours so it isn’t a frozen rock.
Did I mention that this probably isn’t a cake for beginning bakers?
It’s also a cake that requires some essential equipment: two half sheet pans, an 8-inch cake ring, a 9-inch cake ring, parchment paper, acetate sheets, large and small offset spatulas, a kitchen scale, a whisk, at least one silicone spatula, and a stand mixer. And having a chinois would be nice too. These are all baking workhorses.
And you need to make sure there’s a good flat landing spot cleared in your freezer and one in your fridge so that you don’t smush everything you spent that last several days working on.
Can it all be worth it?
13 Ways of Looking Chocolate Mousse Cake
For the whipped caramelized white chocolate ganache:
- 170 grams white chocolate chopped (6 ounces)
- 1 1/2 cups heavy cream (355 ml)
For the salty chocolate shards:
- 57 grams 70% bittersweet chocolate chopped (2 ounces)
- 1/4 teaspoon flaky sea salt
For the flourless chocolate souffle cake:
- 10 large eggs separated
- 280 grams semisweet or bittersweet chocolate melted and cooled (10 ounces)
- 1/4 teaspoon salt
- 250 grams sugar (1 1/4 cups)
For the cocoa soaking syrup:
- 100 grams sugar (1/2 cup)
- 1/2 cup water (118 ml)
- 4 tablespoons cocoa powder sifted (either natural or Dutch-processed is fine)
For the bittersweet chocolate mousse:
- 3 1/2 cups heavy cream (828 ml)
- 255 grams 70% bittersweet chocolate chopped (9 ounces)
- 128 grams 64% bittersweet chocolate chopped (4 1/2 ounces)
- 150 grams sugar (3/4 cup)
- 3 large eggs
- 9 large egg yolks
For the dark chocolate ganache:
- 510 grams semisweet or bittersweet chocolate, preferably no higher than 64% chopped (18 ounces)
- 1 1/2 cups heavy cream (355 ml)
- 1 tablespoon dark rum
For the mirror glaze:
- 50 grams sugar (1/4 cup)
- 2 tablespoons cocoa powder sifted (either natural or Dutch-processed is fine)
- 1 gelatin sheet
- 1 tablespoon glucose or light corn syrup
At least 3 days before you plan to serve the cake:
- Caramelize the white chocolate. Heat oven to 250°F. Line a rimmed baking sheet with a Silpat mat and scatter the chopped white chocolate in a single layer over it. Bake, stirring and spreading the chocolate around every 10 minutes, for about 45 minutes to 1 hour or until the white chocolate has turned a deep golden brown. Don’t worry if the chocolate looks grainy, lumpy, or even chalky at times during the process, eventually it will smooth out (and the last lumpy bits will be smoothed out when making the ganache). If not using right away, transfer to a jar or other airtight container and store at room temperature (will keep for at least a week).
At least 2 days before you plan to serve the cake:
- Make the caramelized white chocolate ganache. Transfer the caramelized white chocolate to a medium heat safe bowl. Heat the cream in a heavy saucepan over medium heat until it comes just to a simmer. Immediately pour the cream over the caramelized white chocolate. Let stand for about 10 minutes to let the hot cream melt the chocolate, then stir until smooth. Cover and refrigerate overnight (or for at least 8 hours) until very cold.
At least 1 day before you plan to serve the cake:
- Make the salty chocolate shards. Place the chopped chocolate in a medium heat safe bowl set over a pan of simmering water and stir occasionally until melted. Place a 12×16-inch piece of parchment paper on a flat work surface. Using an offset spatula, spread the chocolate in a thin even layer over the parchment paper. Sprinkle the sea salt over the chocolate and lay another sheet of parchment paper over the top. Roll a rolling pin over the top of the parchment paper to press the salt into the chocolate. Transfer to the refrigerator or freezer and let it chill until it has hardened, at least a half hour. When the chocolate has hardened, chop into very small irregular pieces and store (immediately) in an airtight container in the refrigerator for up to 2 days. These will melt immediately on contact with your warm hands, so use the back of a chef’s knife or a bench scraper to transfer the chocolate from the parchment to the container to keep your hands and the rest of the kitchen from being covered in melted chocolate.
Make the cake. Preheat the oven to 350°F and place one rack in the center and one in the top third of the oven. Line two half sheet pans with parchment paper and spray with nonstick baking spray (if you’re making this gluten free, don’t use the baking spray that has flour mixed into it).
- In a large bowl, whisk together the egg yolks, coffee, melted chocolate and salt. In the bowl of a stand mixer fitted with a whisk attachment, add the egg whites and beat on medium speed for about 2-3 minutes until soft peaks form. The tines of the whisk should leave a trail in the whites and when you lift the head of the mixer the whites should should peak and droop. With the mixer on medium, add the sugar slooowly, about a tablespoon at a time, until it’s all added. This process should take about 2 minutes. Increase the speed to medium-high and beat until the whites are glossy and smooth and hold their peaks.
- Using a rubber spatula, fold about one-third of the whites into the chocolate-yolk mixture to lighten it. Then gently fold in the rest of the whites until no white streaks remain. Do this carefully. Egg whites are easy to deflate.
- Divide the batter between the two prepared sheet pans. Starting at the corners, spread the batter evenly over the pan with an offset spatula. It doesn’t need to be perfectly smooth, but you want the corners and edges filled in. The batter should be about a 1/2 inch (1 cm) deep.
- Bake the cakes, rotating the pans from front to back and switching between the racks about halfway through, about 16-18 minutes. The cakes should look dry on top and when you touch it with a finger, the top should feel dry and delicate and almost shatter and the cake below should feel moist. Let the cakes cool on wire racks for 10 minutes. At this point you can assemble the cake or wrap the cakes (still in their pans) with plastic wrap and keep at room temperature for one day.
- Make the cocoa soaking syrup. Combine the sugar, water and cocoa powder in a small saucepan and heat over medium-high heat until it comes to a boil, stirring occasionally until the sugar is dissolved. Strain through a fine-mesh strainer and let cool at room temperature. (Can be made up to 3 days in advance and stored in an airtight container in the refrigerator.)
- Make the dark chocolate ganache. Place the chopped chocolate in a large heat safe bowl. Heat the cream in a medium heavy bottomed saucepan until it comes just to a simmer. Immediately pour the hot cream over the chocolate and let stand for about 10-15 minutes to melt the chocolate. Whisk together until the the mixture is smooth.
- Make the bittersweet chocolate mousse. In the bowl of a stand mixer fitted with a whisk attachment, whip the cream on medium-high speed until it holds soft peaks. This should take about 2 minutes. Transfer to another bowl and refrigerate. Wash out the bowl of the stand mixer and the whisk attachment and dry them thoroughly. You’ll need them again soon.
- Place both kinds of chocolate in a large heat safe mixing bowl set over a pan of simmering water and stir until melted.
- Combine the sugar with a 1/4 cup of water in a small heavy bottomed saucepan and bring to a boil. Cook until it reaches 230-240°F on a candy thermometer.
- Meanwhile, combine the eggs and yolks in the bowl of a stand mixer, again, fitted with a whisk attachment and whip at medium-high speed for about 2 to 3 minutes until the mixture looks thick and pale.
- With the mixer running, carefully pour the hot sugar syrup over the eggs, taking care to avoid pouring it directly on the whisk. Increase the speed to high and whip until the mixture has tripled in volume. This should take about 8-10 minutes. Transfer to a large mixing bowl. (Again, wash and dry the stand mixer bowl and whisk attachment.)
- Pour half of the melted chocolate into the egg and sugar mixture, and whisk together until well combined. Fold half of the whipped cream into the chocolate-egg-sugar mixture with a rubber spatula, taking care to avoid deflating it too much. Repeat with the remaining chocolate and whipped cream. It’s best to assemble the cake soon after making the mousse.
- Whip the caramelized white chocolate ganache. Pour the chilled caramelized white chocolate ganache base into the bowl of a stand mixer fitted with a whisk attachment and whip at medium-high speed until it holds soft peaks and is a spreadable consistency. With a rubber spatula, fold in the salty chocolate shards.
- Assemble the cake. Line a 9-inch cake ring with acetate (and tape the sides) to extend the height so that you have a cylinder that’s at least 7 inches tall. Place a 9-inch cardboard cake board in the bottom of the cake ring and tape to secure.
- Using an 8-inch cake ring, cut out 4 8-inch circles from the chocolate soufflé cake. The cake is fragile, so leave it in place after cutting it. Using kitchen shears, cut the parchment paper around the edge of each circle so you have a base to help transfer the cake. Very carefully, take one circle of cake and transfer it to the cake board at the bottom of the cylinder. Don’t worry if it breaks a little in the process, just patch it back together as well as you can. Center the circle of cake as best as you can on the cake board. There should be an even border around the edge of the cake. Using a pastry brush, moisten the cake with 1/4 of the cocoa soaking syrup.
- Using a small offset spatula, spread half of the whipped caramelized white chocolate ganache over the cake, taking care not to push it beyond the edge of the cake.
- Carefully transfer another circle of cake over the whipped ganache. Again, moisten with 1/4 of the soaking syrup. Spread about 1/4 of the dark chocolate ganache over this cake layer, taking care not to let it fall over the side. Spread about half of the bittersweet chocolate mousse over the cake layer and down the sides (the mousse on the sides becomes the outer layer on the sides). Use your small offset spatula to push and spread the mousse down the side between the cake and the pan.
- Carefully transfer another circle of cake over the mousse. Again, moisten with 1/4 of the soaking syrup and spread with 1/4 of the dark chocolate ganache. Spread the remaining whipped caramelized white chocolate ganache in an even layer over the top, taking care not to let it extend beyond the edges of the cake.
- Carefully transfer the final circle of cake over the whipped ganache. Moisten with the remaining soaking syrup. Spread with 1/4 of the dark chocolate ganache. Top with the remaining bittersweet chocolate mousse, again, pushing it down the sides of the cake. You want a smooth layer of mousse on the outside of the cake.
- Make sure you have an even landing spot cleared in your freezer. Transfer the cake to the freezer and freeze overnight.
On the day you want to serve the cake.
- Gently reheat the remaining dark chocolate ganache until soft and spreadable. Remove the cake from the freezer and spread the ganache over the top in an even layer. Return the freezer while you make the mirror glaze.
- Make the mirror glaze. In a small heavy bottomed sauce pan, combine the sugar, cocoa powder, heavy cream and 2 tablespoons of water. Bring just to a simmer and remove from heat. Bloom the gelatin sheet and add to the the hot sugar mixture. Add the glucose (or corn syrup) and mix to combine.
- Remove the cake from the freezer. Pour about half of the mirror glaze over the top of the cake and spread in an even layer with a long offset spatula. Return the cake to the freezer to set for ten minutes. Then remove the cake from the freezer and repeat with the rest of the mirror glaze. Return to the freezer to set for another 10 minutes.
- Remove the cake from the freezer and carefully unmold the cake from the cake ring and remove the acetate. If there are any gaps in the bittersweet chocolate mousse coating on the sides of the cake, don’t panic, carefully warm a long metal spatula and spread the mousse over the gaps to cover.
- Place on a larger cake board or serving plate and garnish with fresh flowers. Thaw in the refrigerator for 6 hours. Remove from the refrigerator for 1 hour before serving to soften.
- Whew! You’re done!